By Scott Moritz

U.S. regulators on Monday charged Dallas Maverick owner and outspoken blogger Mark Cuban with using confidential information in 2004 to sell his stake in Mamma.com, a Montreal search engine now known as Copernic (CNIC). His sale of all 600,000 shares helped Cuban avoid a 10% dive in the stock, or about $750,000 in losses, the government contends.

The Securities and Exchange Commission filed a civil lawsuit against Cuban on Monday. No criminal charges were filed.

Cuban, the biggest shareholder in Mamma.com, was allegedly angered by plans for a private sale of discounted Mamma.com stock, according to the lawsuit filed in U.S. District Court for the Northern District of Texas.

Mamma’s CEO had contacted Cuban to see if he was interested in participating in the so-called PIPE, or private investment in public equity, according to the SEC complaint. Selling the stock at a discount effectively dilutes the stakes held by existing shareholders. Cuban allegedly responded: ”Well, now I’m screwed. I can’t sell,” according to information provided by the Mamma CEO to regulators.

But sell he did, according to the SEC. One minute after hearing the full details of the private investment offer for Mamma.com shares, Cuban allegedly called his Dallas broker and said: “Sell what you can tonight and just get me out the next day.”

The SEC wants Cuban to pay back the $750,000 he avoided in losses after Mamma.com’s shares fell as well as a potential fine of $2.25 million.

Cuban issued a statement Monday saying the charges had no merit. “The government’s claims are false and they will be proven to be so,” he said.

Cuban’s net worth has been estimated to be $2.8 billion. His big jackpot came in 1999 when he sold Broadcast.com to Yahoo (YHOO) for nearly $6 billion, one of the largest cash-outs of the Internet boom.

As the owner of the Mavericks and Internet soapbox Blog Maverick, Cuban has displayed a fiery temperament at times. After a few shouting matches with Mavericks head coach Avery Johnson earlier this year, Cuban fired Johnson, the most successful coach in franchise history, at the end of the NBA season in April.

If skirting securities laws to avoid losing a relatively insignificant amount of money sounds strange, it isn’t, says Scott Friestad, deputy director of enforcement for the SEC.

“It’s not uncommon that the amount of the transaction is not correlated to a person’s financial wherewithal,” said Friestad. “We’ve seen sales worth $15,000 by people with $1 million-a-year salaries.”

By Scott Moritz

The planned advertising partnership between Google (GOOG) and Yahoo (YHOO), which was devised during Microsoft’s (MSFT) unsolicited bid for Yahoo, is headed for a federal antitrust challenge. And that could mean, according to one analyst, that Google could wind up walking away from the deal.

Two days after the Association of National Advertisers sent a letter to the Justice Department opposing the Google-Yahoo ad pact, antitrust regulators hired high-powered attorney Sanford Litvack to lead its legal challenge to block the deal, according to The Wall Street Journal. For a look at what veteran antitrust lawyer Stephen Axinn told CNNMoney.com about Litvack’s hiring and what it means for Google and Yahoo, click here.

Part of Google’s strategy to form a search ad partnership was to keep Yahoo out of Microsoft’s hands. After failing to strike a deal, Microsoft and Yahoo went separate ways and Yahoo continued to pursue the ad partnership with Google.

Now, it might make more sense for Google to withdraw the partnership plan rather than fight the Justice Department in court, said Stifel Nicolaus analyst Blair Levin. Even though Google and Yahoo don’t need regulatory approval for their ad arrangement, Levin wrote in a research note Tuesday that “it would be risky…to proceed if they are getting signals that the agency has serious concerns.”

In addition, another analyst suggested that Google would not suffer too much if its Yahoo search ad plans were killed.  Cowen analyst Jim Friedland wrote in a note that he thought a Yahoo deal would only boost Google’s earnings before charges by 1% to 2% in the first 12 months of the deal.

Representatives for Google and Yahoo did not immediately return calls seeking comment.

But Google has already voluntarily delayed the start of the joint advertising process until October so regulators could examine its potential impact. “We are confident that the arrangement is beneficial to competition,” Google said in statement Tuesday.

The search ad partnership was first proposed in June when Microsoft went public with its offer to acquire Yahoo. The ad arrangement called for Google to run its text ads next to Yahoo’s search results. In exchange, Google would pay Yahoo an unspecified cut of the search revenue. But from the beginning, the deal between the top two Internet search services invited antitrust scrutiny and, as it turned out, some industry opposition.

After reviewing the deal, the ANA said in its letter to the Justice Department that Google and Yahoo would control 90% of the search ad market. “The partnership will likely diminish competition, increase concentration of market power, limit choices currently available and potentially raise prices to advertisers for high quality, affordable search advertising,” the ANA wrote.

Google responded indirectly to the ANA letter saying that “While there has been a lot of speculation about this agreement’s potential impact on advertisers or ad prices, we think it would be premature for regulators to halt the agreement before we implement it and everyone can judge the actual impact.”

In somewhat related news, Google, in an attempt to ease concerns among regulators, announced on its official blog late Monday that it has decided to shorten the length of time it keeps users’ Web information to 9 months from a previous target of 18 months. Google says it compiles some user information like Internet addresses and search history to better match ads to user interests.

By Michal Lev-Ram

The Microhoo deal is still far from over, but you can bet every one of Yahoo’s 14,300 employees are wondering what the $44.6 billion bid from Microsoft means for them.

The fate of Yahoo’s top executives — co-founders Jerry Yang and David Filo and president Susan Decker — remains unclear. Will Microsoft clean house or try to retain some of Yahoo’s (YHOO) higher-ups? More importantly, will top Yahoos even want a corner office in Redmond?

Whatever happens under a new regime, Yang, Filo and Decker will be provided for financially, to say the least. Based on Microsoft’s (MSFT) bid to buy Yahoo at $31 a share (a 62 percent premium to the share price when the offer was made last Friday), here’s how the three head Yahoos would fare, according to executive compensation research firm Equilar and Securities and Exchange Commission filings:

• Jerry Yang: Yahoo’s CEO indirectly owns 43,489,864 shares held in trust and 9,314,390 held in a family partnership of Yahoo. If these shares were purchased for $31, they would have a combined value of over $1.6 billion. This value doesn’t include the 6,310 shares held by Yang’s wife, for which he disclaims beneficial ownership.
• David Filo: Filo stays out of the limelight but directly owns close to 80,000,000 shares of Yahoo. At the proposed $31 price per share, they would be worth more than $2.4 billion.
• Susan Decker: Decker holds an estimated 634,676 shares directly and 6,161,667 options. Under Microsoft’s valuation, they’d have a value of over $54 million.

But don’t expect any “golden parachutes” for these Yahoos — according to research firm Equilar and company records, there’s no evidence Yahoo would give its execs cash severance benefits in the event of a take-over. However, the company does have an agreement with Decker stating that some of her previously vested options will remain exercisable for an additional three years if she leaves the company.

As for majority of Yahoo’s employees — the non-billionaires — it’s not clear how they would fare under a Microsoft acquisition. The struggling search engine (and I mean Yahoo) had already said it would lay off 1,000, or 7 percent, of its workforce sometime this month. It’s likely Microsoft would make more cuts should the deal go through.