By Michal Lev-Ram

When Sprint Nextel CEO Dan Hesse joined the wireless company last December, he inherited a backlog of problems. Among them: The logistical nightmare of managing two different networks formed by Sprint’s merger with Nextel, a high rate of subscriber defections and a bad (okay, horrible) reputation for customer service.

At his first conference call with analysts in February after Sprint (S) announced disappointing fourth-quarter earnings, Hesse himself admitted that “the issues we face are more difficult than what I had expected to find.”

But that didn’t stop the former AT&T (T) executive from quickly implementing some much-needed changes. Within five months, Hesse has cut costs by closing 8 percent of Sprint’s retail stores and laying off nearly 7% of the staff. He also made senior management changes, launched a new unlimited voice and data plan, and just this week inked a joint WiMax venture with Clearwire (CLWR) and a slew of high-profile investors.

Now, as Sprint prepares to release its first-quarter earnings results Monday, investors are looking to Hesse to see what he’ll do next to turn the wireless carrier around.

“So far the read on him is cautiously optimistic,” says RBC Capital Markets analyst Jonathan Atkin. “He’s taken prudent steps to evaluate what the issues are, and made progress on his checklist - including the critical item of how to move forward with WiMax.”

Sprint’s investment in WiMax - a next-generation network that promises faster speeds well-suited for data services like web browsing and music downloads - has been a main point of contention among investors. Under former chief executive Gary Forsee, the company poured about $5 billion into the technology, only to find its cutting-edge service bogged down by delays and an inability to seal a WiMax partnership with broadband Internet provider Clearwire.

But last Wednesday the two companies announced they had finally come to an agreement and would combine their wireless broadband operations to create a $14.55 billion venture. Intel (INTC), Google (GOOG) and a handful of other companies have agreed to invest $3.2 billion in the new company.

In an interview with Fortune earlier this week, Hesse said the upcoming WiMax service will give Sprint a “differentiating advantage.”

“This allows us to be the only company to offer 4G [fourth-generation network] services,” said Hesse. “WiMax as a technology is available now and it works now.”

Of course, it’s still not clear exactly when the new service will be available to Sprint customers, though the Clearwire joint venture is expected to close by year-end. Sprint rivals AT&T and Verizon (VZ) have said they are committing to a competing fourth-generation network technology called Long Term Evolution, or LTE, which is expected to become available around 2010.

With its increasingly narrower time-to-market advantage, WiMax is still far from a guaranteed success. And in the meantime, Hesse has his hands full trying to put out other fires.

Come Monday, investors will be looking for news regarding Sprint’s core business, selling voice and data services on its CDMA network. In contrast to the globally used GSM standard, CDMA has been bleeding customers. Subscribers have also been defecting from the iDEN network the company inherited when it merged with push-to-talk service provider Nextel in 2005.

“We are still looking for evidence that Sprint is generating positive momentum around its postpaid marketing to return back to positive postpaid subscriber growth over time,” Citigroup analyst Michael Rollins wrote in a recent report.

In an effort to retain and attract customers, Hesse has already embarked on a new brand campaign that aims to position Sprint as the “superior network.” But Rollins says that the company hasn’t “gone far enough to differentiate its message on network quality perception or price.”

Hesse has also said that improving Sprint’s customer service is one of his top priorities.

“Not only are we not attracting enough new customers, but our existing customers are leaving us at too big a rate,” Hesse had told Fortune in an interview last February, after Sprint posted a fourth-quarter loss of $29.5 billion and a continued decline in subscriber numbers.

There’s no question Hesse has his work cut out for him. But if his first five months in at the company’s helm are an indication of what’s to come, you can count on seeing more changes at the number three mobile operator - for better or worse.

By Yi-Wyn Yen

Google may be getting cold feet. In a last-ditch effort to avoid a merger with Microsoft, Yahoo said it was considering teaming with Google in a search advertising deal. But some Google executives are now questioning whether that’s a good idea, the Wall Street Journal reported Thursday.

One major hurdle: A Google-Yahoo tieup could face tough scrutiny from regulators in Washington and the European Union. Last month Yahoo (YHOO) ran a two-week test displaying some of Google’s (GOOG) search ads on Yahoo’s homepage. Both Yahoo and Google executives said the experiment went well. The two are reportedly in talks to outsource Google’s search technology in a non-exclusive arrangement.

Spokespeople from both Google and Yahoo declined to comment.

Google may have wedged its way into the mix in order to break up Microsoft (MSFT) and Yahoo. Microsoft CEO Steve Ballmer admitted that Google was a factor when the software giant walked away from its $47.5 billion offer last Saturday. In a letter to Yahoo CEO Jerry Yang, Ballmer said his company would not be willing to deal with the “host of regulatory and legal problems” that it would inevitably inherit if Yahoo partnered with Google.

Last month Microsoft’s general counsel Brad Smith lashed out at the two big Internet sites for partnering even in a limited test. He argued that a Google-Yahoo combo would give Google a 90% share of online search advertising and that “this would make the market far less competitive. It would be fair to say that Microsoft would aggressively lobby against a long-term partnership between Google and Yahoo.

Microsoft was one of Google’s biggest detractors when the search giant said it was going to buy DoubleClick, the top firm in online display advertising. Google got approval from both the Federal Trade Commission and the European Committee to acquire DoubleClick, but the approval took the big G nearly a whole year.

Both the FTC and the European Committee ruled that text-based search advertising and display advertising, which is the preferred way that big brands like to advertise, are two different markets, and therefore the merger was not anticompetitive. But regulators may be more wary if the two biggest players in search want to team up.

“Google has incredible chutzpa,” said Jeffrey Chester, the executive director of the Center for Digital Democracy. The public interest group had opposed Google’s DoubleClick deal because it would give Google an overwhelming lead in online advertising.

Chester said both Microsoft and Google have approached him to support their political message on the Hill. He has not yet endorsed either party, and is waiting for a deal - whether it’s Microsoft and Yahoo or Google and Yahoo - to be announced.

However, Chester said he is wary of a Google-Yahoo tieup. “Whatever happens, we don’t want Google to operate Yahoo out of its back pocket,” Chester said. “Whether or not regulators do something about it, we’ll do something.”

By Yi-Wyn Yen

In the aftermath of the Yahoo and Microsoft dust up, News Corp. says it is staying out of the mess.

News Corp. (NWS) had previously been linked to Yahoo (YHOO) and then switched camps to join Microsoft (MSFT) in its pursuit to acquire Yahoo. Microsoft eventually went it alone and four days ago, the behemoth walked away from its $47.5 billion offer with plans to look into alternatives to beef up its online ad unit. News Corp., which owns social networking site MySpace, shot down any rumors that it will partner with Microsoft.

“We’re not in discussions with Microsoft. There are no discussions,” said Peter Chernin, chief operating officer of News Corp. during an earnings call Wednesday with shareholders.

Chernin said that the company holds “regular conversations with everyone in the space,” but has not held any talks with Yahoo or Time Warner’s AOL (TWX) in the last “couple weeks.” Added CEO Rupert Murdoch, “Nor have I.”

In an effort to stave off Microsoft’s unsolicited bid, Yahoo said it was pursuing other deals like partnering with AOL or Google (GOOG). At one point, Yahoo also considered a tie-up with News Corp.’s MySpace. With its massive and highly-engaged audience, a MySpace partnership was seen as way to attract advertisers and help bring economies of scale for either Microsoft and Yahoo. Though Microsoft has a minor stake in Facebook, neither have developed a major social networking presence.

MySpace may generate millions of page views and visitors to its site, but it continues to struggle with growing its sales. News Corp’s Fox Interactive Media, which includes MySpace and other online properties like gaming site IGN and photo-sharing site Photobucket, will miss its $1 billion revenue target for its 2008 fiscal year that ends June 30. Chernin said the company will fall short of its projections by 10%.

Fox Interactive relies on online advertising to generate revenue. MySpace, which makes up the bulk of Fox Interactive’s revenues, generated $66 million in its fiscal third quarter from an ad-sharing deal with Google.

Chernin explained that there’s a learning curve to make money off of social networking sites. “Social media has only been around for a few years,” he said. “It’s still difficult to quantify the economic value of a friend. We’re working with major brands and agencies to educate and experiment with social media.”

Fox Interactive is still in its growing phase, Chernin said. “We will continue to invest. We’re already invested in [third-party] applications, MySpace Music, and new development tools for the homepage,” he said. “It’s too soon to be milking for margins right now. We need to focus on growth.”

By Scott Moritz

WiMax is facing a now-or-never moment as Sprint (S) and Clearwire (CLWR) try to finalize terms of a multi-player joint venture.

Nearly five months into his job as Sprint chief, Dan Hesse has a chance to set Sprint free from an expensive network buildout commitment, and simultaneously spark the WiMax revolution. Sprint and Clearwire are set to announce the formation of a WiMax joint venture involving Comcast (CMCSA), Time Warner Cable (TWC) and funding from Intel (INTC) and Google (GOOG). The announcement could come as early as 6 a.m. Wednesday, according to one source familiar with the plan. Sprint and Clearwire shares surged 7% Tuesday afternoon on raised expectations of an announcement.

It is also possible that the deal could come later, or never, if the parties can’t ultimately agree on who controls the network. Google, for example, has been a uneasy participant, say people familiar with the company. The other players would like to attach Google’s winning name to this ambitious project, but apparently the Net giant has waffled in recent weeks, backing out at one point, then opting back in.

Those watching the unsteady progress of WiMax can’t be brimming with confidence after watching other tech deals disolve. As Microsoft’s three-month failure to woo Yahoo proved, lots of big egos, some forceful approaches and a weakening economy don’t add up to easy negotiations.

Once heralded as the next big thing in mobile broadband, WiMax was to be the successor to WiFi, an untethered Net connection that would usher in a new generation of mobile devices and portable applications.

There have been a couple bumps along the road to WiMax success however. The development of a national network operating on a unified standard has largely been in the hands of two disappointing tech shops: Sprint and Clearwire. The second setback is that the two largest wireless players, AT&T (T) and Verizon (VZ), are pursuing a different technology, called long term evolution or LTE.

The WiMax move would also help move Sprint further down the split-up path. Hesse, with the urgings of some of Sprint’s bigger investors like Ralph Whitworth of Relational Investors, has been mulling a breakup of the No.3 wireless shop. Among the options is the sale of Nextel’s iDEN network, reported to have caught the interest of former Nextel co-founder Morgan O’Brien who runs a public safety networking venture called Cyren Call.

Another step would be the sale of Sprint’s long-distance business, the Global Markets Group. While some analysts say separating the company’s seemingly core network would be nearly impossible, others argue that Sprint is not in a position to turn down any offers at this point.

But the first piece of the splinter strategy for Sprint is WiMax. Hesse inherited the WiMax business, known as Xohm when he took over the CEO job left by Gary Forsee. Forsee staked the company’s future on the promising mobile wireless broadband technology. But the $5 billion cost to build a WiMax network was too much for Sprint, already beset by massive customer defections stemming from its failed merger with Nextel.

The pairing of Sprint’s spectrum and WiMax technology with Clearwire was proposed last year. Sprint needed to get the costs off its books and Clearwire needed a big partner to help make WiMax happen and lend some financial support.

Intel Capital holds about a 25% stake in Clearwire. Clearwire founder Craig McCaw is the largest single shareholder, with a majority of the outstanding shares.

Comcast and Time Warner Cable have identified wireless broadband as a huge opportunity to deliver services like video and calling to a new generation of mobile devices. Last week Comcast raised $2 billion in a bond sale that analysts say signals the Philly cable giant’s readiness to jump into the WiMax venture.

Intel and Google have high hopes that a new national network would open up a mass market for their products and services.

Without this bold joint venture alliance, WiMax faces a bleak future, as other fourth-generation technologies gain ground. The deal could save WiMax from being another promising yet soon forgotten new next thing.

By Scott Moritz

Yahoo (YHOO) chief Jerry Yang has lost a deal and gained some enemies.

Yes, Microsoft (MSFT) walked away from the proposed blockbuster merger - but no, the new enemy is not Microsoft CEO Steve Ballmer.

Instead, it’s Gordon Crawford of Capital Research Global Investors, a holder of 6% of Yahoo’s shares.

Crawford voiced his extreme disappointment in Yang in press reports, including a piece in Tuesday’s Wall Street Journal taking direct aim at Yang and his hamhanded treatment of the Microsoft offer. “I think he overplayed a weak hand,” Crawford told the Journal.

He’s not alone. Other Yahoo investors have taken issue with the way Yang tried to hardball his way to a higher bid.

“This $37 price was ridiculous,” said one Yahoo investor referring to Yang’s deal-breaking counter offer to Ballmer in Seattle on Saturday. “I would have had no problem taking the thing at $31,” the investor said.

Yang has since protested that the $37 pitch was merely a starting point to get the talks going. But after three months, two rejections and a ad outsourcing pact with rival Google (GOOG), Microsoft’s Ballmer decided to use Yang’s starter as an end to the discussions.

The move puts Yang under the spotlight as big investors and small watched Yahoo’s value shrink - on Monday, the stock closed 15% below its closing price Friday.

“This is a clear example where the management didn’t have the best interest of the shareholders at heart. I think a lot of shareholders would have been very happy to do this deal at $33,” said Jacob Internet Fund manager and Yahoo shareholder Darren Chervitz, in Fortune Techland story Monday.

Another big stakeholder, Bill Miller of Legg Mason, whose firm swung to a $256 million loss in the first quarter on bad bets in Countrywide and Bear Stearns, is also feeling the pressure of having more than a 6% position in Yahoo. Miller told Bloomberg that he’s holding out hope that Microsoft and Yahoo can rekindle the discussions.

“There’s probably a lot of people jumping up and down today,” Miller told Bloomberg.

He expects Microsoft to come back. “If I’m sitting in their shoes, I’ll go away and see what happens,” Miller said . “I can come back and the worst case is, I’ll pay six months more of my free cash flow.”

For Microsoft, while the software giant may have averted overpaying for Yahoo, it hasn’t solved the bigger problem: How to compete with Google for the Internet advertising bounty.

Meanwhile, Yang and Yahoo will have a chance to feel some of the investor blowback at the annual shareholder meeting scheduled for July 3.

Observers such as Fortune’s Go West columnist Adam Lashinsky ask: “What will happen to Yahoo’s board? Will angry shareholders kick out its value-destroying board?”

By Scott Moritz

Comcast (CMCSA) has raised $2 billion through a bond sale as the company explores its wireless broadband options, among other things.

The Philadelphia cable giant was able to increase its planned debt offering of $1.5 billion to $2 billion on strong demand for the note, according to Bloomberg News. The news comes a day after the company posted solid first quarter earnings and said it was still planning to move ahead in wireless data.

On the earnings conference call with analysts, Comcast executives said they would take action to to preserve its credit rating.

“We are going to be very disciplined in our capital structures, and do things that make a lot of sense,” Comcast executives said Thursday.

As of March 31, Comcast’s total debt was $37.4 billion, according to a regulatory filing.

Some analysts says the financing move is a good sign that Comcast is getting closer to reaching some sort of agreement on a proposed WiMax joint venture between Sprint (S) and Clearwire (CLWR). Other players that have been involved in those discussions include Time Warner Cable (TWC), Intel (INTC) and Google (GOOG).

Comcast has a big role in the fate of a national WiMax network. If the joint venture fails to find enough funding or participants, the so-called 4G wireless technology faces falling behind the long term evolution or LTE technology that AT&T (T) and Verizon Wireless (VZ) have already committed to.

By Yi-Wyn Yen

The deadline that Microsoft set three weeks ago for Yahoo (YHOO) to accept its buyout offer passed this weekend without either side making a move. While some analysts expect Microsoft to launch a hostile bid, it’s possible that CEO Steve Ballmer will follow through on his threat and walk away from the deal.

The three-month-old battle between Microsoft and Yahoo could come to a head fast. Yahoo has repeatedly rebuffed Microsoft and demanded a higher price - step that Ballmer has said he won’t take.

Earlier news reports indicated that Yahoo’s board of directors would meet on Sunday to consider their options, but there was no official confirmation of a meeting. The Wall Street Journal reported Monday that Microsoft and Yahoo did not have direct contact over the weekend. Microsoft could move as early as Tuesday, according to the Journal.

At stake is Microsoft and Yahoo’s ability to compete with Google as billions of advertising dollars continue to flood the Internet. As Google has risen to become the dominant online ad player, Microsoft and Yahoo have both struggled to gain traction. Most analysts think a merger is the best way for Microsoft and Yahoo to compete with Google.

Microsoft kicked off the battle in late January when it made an unsolicited cash-and-stock bid for Yahoo that was originally valued at $31 a share, or $45 billion. The deal’s value has since dropped to $29.64 as Microsoft’s shares have fallen.

While Microsoft and Yahoo executives have met to discuss the bid, Yahoo has so far spurned Microsoft. Yahoo CEO Jerry Yang has said he’s not opposed to a Microsoft buyout, but argues that the offer “substantially undervalues” Yahoo. To force Microsoft (MSFT) to up the ante, Yahoo has discussed a variety of tieups with Time Warner, News Corp. and Google in recent months.

“Our board and management team continue to be open to any and all alternatives, including a sale to Microsoft,” Yang said last week, when Yahoo reported first-quarter earnings that beat estimates.

Talks between Microsoft and Yahoo have been anything but friendly. Three weeks ago, Microsoft CEO Steve Ballmer issued the ultimatum that expired Saturday. On Thursday, when Microsoft also reported better-than-expected profits, chief financial officer Chris Liddell voiced his frustration with Yahoo’s recalcitrance - and suggested the company’s prepared to go to war or walk away.

“Unless we make progress with Yahoo towards an agreement by this weekend, we will reconsider our alternatives,” said Liddell, suggesting that Microsoft will makes its decision know next week. “The transaction has been anything but speedy as is being characterized by what would appear to be [Yahoo's] unrealistic expectations of value.”

Now that Yahoo has missed Microsoft’s deadline, one of the following three scenarios is likely:

• Microsoft turns up the heat and launches a proxy battle. The company has already hired a proxy firm and reportedly nominated candidates to an alternative board of directors. That slate would come up for a vote at Yahoo’s annual shareholder meeting, sometime before the end of July. (In an attempt to stymie Microsoft, Yahoo delayed its original March 14 shareholder meeting and has not yet announced a new date. According to Yahoo’s bylaws, however, the company must hold the meeting every 13 months, which means by the end of July.)
• Microsoft walks away. The Journalreported that this seems unlikely, although abandoning the bid could increase the pressure on Yahoo to come to the negotiating table. If Microsoft drops its bid for Yahoo, the company is likely to continue acquiring online ad companies. In the past 11 months, Microsoft has spent more than $6 billion to acquire aQuantive and Rapt.
• Status quo. Microsoft extends the proxy deadline while Yahoo tries to convince its shareholders that an alliance with Time Warner’s AOL or Google is more desirable.

Microsoft CEO Steve Ballmer doesn’t want to bid against himself by upping the original deal. Photo courtesy of Microsoft.

It’s not clear how much Microsoft could accomplish without Yahoo. Ballmer clearly sees Yahoo as the ammunition he needs to take on Google as online advertising spend skyrockets. According to eMarketer, advertisers worldwide spent $41 billion online in 2007 — a figure that is expected to double through 2011 as advertisers chase after consumers who are spending more time on the Web and less time watching TV, reading newspapers or listening to the radio. Google controls 40% of the overall market while Yahoo and Microsoft’s MSN have 15% and 5.2%, respectively. Google commands an even greater share in the lucrative search-ad business, with 58.7% of the market compared to 18.1% for Yahoo and 12% for MSN, according to the latest Nielsen data.

Microsoft fears that Google, with its March acquisition of DoubleClick, the world’s biggest online ad server company and big player in the increasingly lucrative market for online display ads, will seize an even bigger portion of the ad market as MSN falls further behind.

Microsoft isn’t the only one worried about Google. A number of media and Internet giants are now circling Yahoo — one of the last independent large-scale online players. “Microsoft’s forcing…everyone to make a move,” says Frank Addante, CEO of Rubicon Project, which helps publishers manage their online ad inventory.

Time Warner (TWX), which owns Fortune.com and CNNMoney, has pursued a deal that would fold AOL into Yahoo in exchange for a 20% stake. Along with aligning with AOL, Yahoo is also looking into outsourcing search advertising to market leader Google (GOOG). Last week Yahoo finished a two-week test that ran Google ads for searches on Yahoo’s homepage. The Justice Dept. is reportedly investigating the test for possible antitrust violations.

News Corp. has approached the deal from different angles. Yahoo and Rupert Murdoch’s News Corp. (NWS) held preliminary talks about a possible partnership after Yahoo rejected Microsoft’s bid. When those discussions stalled, News Corp. began talking with Microsoft about a three-way alliance that would combine News Corp.’s social networking site, MySpace, MSN and Yahoo.

Many analysts argue that ultimately a Microsoft-Yahoo combination is the best option for Yahoo shareholders — and for Microsoft in its war with Google. Wrote Bernstein Research analyst Jeffrey Lindsay in a note to investors on Friday: “We expect the acquisition scenario to play out before the end of July (the theoretical outer limit for the Yahoo! shareholder meeting) and think the outcome is very likely to be a sale to Microsoft at a slightly improved price.”

Yahoo has until Saturday to accept Microsoft’s offer. Courtesy of Yahoo.

By Yi-Wyn Yen

The Microsoft-Yahoo standoff could get ugly fast.

Saturday is the deadline that Microsoft set three weeks ago for Yahoo (YHOO) to accept its buyout offer - or face the possibility of a hostile bid or a decision by Microsoft to abandon the deal altogether. The April 26 deadline brings to a head three months of high-profile jockeying during which Yahoo has repeatedly rebuffed Microsoft and demanded a better price.

At stake is Microsoft and Yahoo’s ability to compete with Google as billions of dollars worth of advertising dollars continue to flood the Internet. As Google has risen to become the dominant online ad player, Microsoft and Yahoo have both struggled to gain traction. Most analysts think a merger is the best way for Microsoft and Yahoo to compete with Google.

Microsoft kicked off the battle in late January when it made an unsolicited cash-and-stock bid for Yahoo that was originally valued at $31 a share, or $45 billion. The deal’s value has since dropped to $29.64 as Microsoft’s shares have fallen.

While Microsoft and Yahoo executives have met to discuss the bid, Yahoo has so far spurned Microsoft. Yahoo CEO Jerry Yang has said he’s not opposed to a Microsoft buyout, but argues that the offer “substantially undervalues” Yahoo. To force Microsoft (MSFT) to up the ante, Yahoo has discussed a variety of tieups with Time Warner, News Corp. and Google in recent months.

“Our board and management team continue to be open to any and all alternatives, including a sale to Microsoft,” Yang said on Tuesday, when Yahoo reported first-quarter earnings that beat estimates.

Talks between Microsoft and Yahoo have been anything but friendly. Three weeks ago, Microsoft CEO Steve Ballmer issued the ultimatum that expires Saturday. On Thursday, when Microsoft also reported better-than-expected profits, chief financial officer Chris Liddell voiced his frustration with Yahoo’s recalcitrance - and suggested the company’s prepared to go to war or walk away.

“Unless we make progress with Yahoo towards an agreement by this weekend, we will reconsider our alternatives,” said Liddell, suggesting that Microsoft will makes its decision know next week. “The transaction has been anything but speedy as is being characterized by what would appear to be [Yahoo's] unrealistic expectations of value.”

If Yahoo doesn’t accept Microsoft’s offer by the Saturday deadline, one of the following three scenarios is likely:

• Microsoft walks away. In this case, Microsoft will likely continue to spend money acquiring other online ad companies. In the past 11 months, Microsoft has spent more than $6 billion to acquire aQuantive and Rapt.
• Microsoft turns up the heat and launches a proxy battle. The company has already hired a proxy firm and reportedly nominated 10 candidates and three alternates to its own alternative board. The Wall Street Journal reported that the 10 nominees include former Nextel CEO John Chapple, former Grey Global Group CEO Edward Meyer, former Adelphia Communications chief financial officer Vanessa Wittman, and Jaynie Studenmund, a former executive at Overture Services, the online ad company acquired by Yahoo.
• Status quo. Microsoft extends the proxy deadline while Yahoo tries to convince its shareholders that an alliance with Time Warner’s AOL or Google is more desirable.

Microsoft CEO Steve Ballmer doesn’t want to bid against himself by upping the original deal. Courtesy of Microsoft.

Microsoft clearly needs Yahoo. Ballmer sees the No 2. Internet portal as the ammunition he needs to take on Google as online advertising spend skyrockets. According to eMarketer, advertisers worldwide spent $41 billion online in 2007 — a figure that is expected to double through 2011 as advertisers chase after consumers who are spending more time on the Web and less time watching TV, reading newspapers or listening to the radio. Google controls 40% of the overall market while Yahoo and Microsoft’s MSN have 15% and 5.2%, respectively. Google commands an even greater share in the lucrative search-ad business, with 58.7% of the market compared to 18.1% for Yahoo and 12% for MSN, according to the latest Nielsen data.

Microsoft fears that Google, with its March acquisition of DoubleClick, the world’s biggest online ad server company and big player in the increasingly lucrative market for online display ads, will seize an even bigger portion of the ad market as MSN falls further behind.

Microsoft isn’t the only one worried about Google. A number of media and Internet giants are now circling Yahoo — one of the last independent large-scale online players. “Microsoft’s forcing…everyone to make a move,” says Frank Addante, CEO of Rubicon Project, which helps publishers manage their online ad inventory.

Time Warner (TWX), which owns Fortune.com and CNNMoney, has pursued a deal that would fold AOL into Yahoo in exchange for a 20% stake. Along with aligning with AOL, Yahoo is also looking into outsourcing search advertising to market leader Google (GOOG). Earlier this week Yahoo finished a two-week test that ran Google ads for searches on Yahoo’s homepage. The Justice Dept. is reportedly investigating the test for possible antitrust violations.

News Corp. has approached the deal from different angles. Yahoo and Rupert Murdoch’s News Corp. (NWS) held preliminary talks about a possible partnership after Yahoo rejected Microsoft’s bid. When those discussions stalled, News Corp. began talking with Microsoft about a three-way alliance that would combine News Corp.’s social networking site, MySpace, MSN and Yahoo.

Many analysts argue that ultimately a Microsoft-Yahoo combination is the best option for Yahoo shareholders — and for Microsoft in its war with Google. Wrote Bernstein Research analyst Jeffrey Lindsay in a client note Friday: “We expect the acquisition scenario to play out before the end of July (the theoretical outer limit for the Yahoo! shareholder meeting) and think the outcome is very likely to be a sale to Microsoft at a slightly improved price.”

Microsoft (MSFT) signaled its ready to play hardball with Yahoo (YHOO) in its bid to acquire the Internet giant, and antitrust regulators are scrutinizing a trial advertising partnership that Google (GOOG) and Yahoo recently struck.

Microsoft put some substance behind its threat to take its three-month-old buyout offer to Yahoo shareholders by naming 13 people as potential candidates to the company’s board, according to Thursday’s The Wall Street Journal.

The list includes former Nextel Partners CEO John Chapple; Edward Meyer, former chief of Grey Global Group; Jaynie Studenmund, the former chief operating officer at Overture Services, a company Yahoo acquired a few years ago; and former Adelphia Chief financial officer Vanessa Wittman, the Journal reported.

Microsoft’s tougher stance comes amid news reports that the Justice Department is looking into Yahoo’s outsourcing of some of its advertising to Google. The companies’ two-week trial ended Wednesday. Yahoo has said it involved about 3% of its search results.

Yahoo has been looking for ways to reduce the cost of operating its search service and, in an effort to thwart Microsoft, to demonstrate it can thrive as a standalone business. But the cooperation between the No.1 and No.2 two search engine shops immediately raised anticompetitive flags when the pact was announced earlier this month.

Google says it “informed the Justice Department before we launched this test, and we have been responsive to their questions about it,” according to the Los Angeles Times. Yahoo said it too had given the Justice Department a heads up prior to the test, according to the Times report.

Microsoft has given Yahoo until Saturday to come up with a counter proposal or answer to its $43 billion takeover offer.

By Scott Moritz, writer

The yelling phase of the proposed Microsoft/Yahoo merger got a bit louder as Yahoo (YHOO) turned in good numbers ahead of the deal negotiation deadline.

In the wake of a solid first quarter performance from Yahoo Tuesday, Microsoft (MSFT) chief Steve Ballmer said his company was standing pat on its original $31 a share unsolicited takeover offer. Microsoft has given Yahoo until Saturday to come to the table with a counter proposal, or face a proxy battle.

“We know what Yahoo is worth to us. We offered a lot of money: $44 billion,” Ballmer said in Milan Wednesday, according to a Reuters report. “If their board thinks that’s fair, great. If not, we’ll move forward,” Ballmer said.

Ballmer is likely waiting to see what Yahoo does come Saturday — the end of the three-week period Microsoft gave Yahoo to consider its options. Microsoft has threatened to start a proxy fight if the two companies fail to come to terms. This would open up an ugly process where Microsoft takes its appeal to shareholders calling for the ouster of Yahoo’s top management and key board members.

Last week, Yahoo rejected the Microsoft bid for a second time saying the proposal undervalued the company. Yahoo also held discussions with Time Warner (TWX) about a deal involving a 20% stake to be held by Time Warner in exchange for AOL and a pile of cash for share buybacks.

But many analysts and investors favor a more amicable conclusion that seems to call for a slightly sweeter offer from Microsoft, either a price higher than $31 a share or an all-cash offer.

Yahoo’s earnings Tuesday, while far from dazzling, did show that the company is not deteriorating as quickly as Microsoft may have suggested. Both companies, however, continue to lose business to Google (GOOG) a point that industry observers say makes the Microsoft Yahoo merger a growing necessity.

The trouble for Yahoo is that it must convince Microsoft to outbid itself, says Darren Chervitz analyst with the Jacob Internet Fund, a big Yahoo investor.

It’s well known that Yahoo has long been losing Net search traffic to Google. And by passing on the acquisition of Facebook last year, they’ve done little to improve their competitive position, says Chervitz.

And for its part, Microsoft has gained very little traction on the Internet. Efforts like MSN mail and .Net haven’t exactly hit any jackpots. Meanwhile, Google has expanded into Microsoft’s software domain with word processing and other office applications available to users online for free.

An even bigger threat to Microsoft is Google’s push into wireless applications. The Google-sponsored Android project hopes to create an operating system for a new generation of mobile devices, a direct threat to Microsoft’s Windows Mobile system. Microsoft can’t easily afford to miss the mobile Internet opportunity, says Chervitz.

“Yahoo,” says Chervitz, “is the only acquisition that gets Microsoft into the game.”