Two of the nation's savviest investors disclosed in filings with the Securities and Exchange Commission yesterday that they have increased their stakes in media companies that have become the target of takeover speculation.

Arbitrageur Ivan F. Boesky said he has increased his stake in Storer Communications Inc. to 9.6 percent, or 1.66 million shares. Boesky said he made net purchases of 848,800 shares between May 22 and July 18 at prices ranging from $74.25 a share to $75.625. Storer, a Miami-based media company, received a takeover bid worth about $2.1 billion last week from Comcast Corp., the nation's 16th-largest cable operator. Earlier this year, Storer agreed to be acquired in a management buyout that could be derailed by the new offer.

Meanwhile, an investment group led by Robert M. Bass, of the Texas Bass brothers, and San Francisco Partners II disclosed that it holds an 8 percent stake in Cincinnati-based Taft Broadcasting Co. Taft immediately issued a statement saying it is not for sale and is determined to remain independent. Bass said he owns 722,000 Taft common shares, including 660,800 purchased from June 3 through July 19 at prices ranging from $72.06 to $82.89 a share. The investor group said it plans to "evaluate the business and prospects of Taft and may present to the company's management its views as a shareholder with respect to Taft's policies and decisions."