Updated from 9:44 a.m.Mamma.com ( MAMA) dropped 13% Friday after one of the company's best-known backers liquidated his stake. Dallas Mavericks owner Mark Cuban reported the move in a schedule 13-G filing Thursday with the Securities and Exchange Commission. Cuban previously reported a 6.3% stake, with beneficial ownership at March 4 of 600,000 common shares of the Montreal-based company. "I bought the company because they were focused on growing organically," Cuban told TheStreet.com in a Friday email. "They decided they wanted to grow through acquisitions, and to also do additional equity placements that would lead to dilution of existing shareholders. I didn't see that as the best approach, so I sold my shares." The news comes just two days after the search engine operator sold $16.6 million worth of stock and warrants at a discount in a private placement. Mamma said at the time it would use the cash for acquisitions. Mamma.com shares have enjoyed a wild ride over the last year. Interest in the company, which competes with Internet giants ranging from Google and Microsoft ( MSFT) to AskJeeves ( ASKJ) and LookSmart ( LOOK), surged in March after Cuban said he took a stake in the company. Cuban is highly regarded among Net investors because he sold Broadcast.com to Yahoo! ( YHOO) for $4 billion during the turn-of-the-century tech boom. Shares of Mamma had generally traded in the low single digits before then, but early March brought a day when the stock jumped 155% in mind-boggling volume. The SEC said soon after that it was examining trading in Mamma.com. On Friday, the stock slipped $1.49 to $10.33.