The market for media properties continued to sizzle yesterday, as a management-investor group offered to acquire Multimedia Inc. in a leveraged buyout worth an estimated $500 million.

Meanwhile, Taft Broadcasting said it agreed to pay $755 million for five television stations and seven radio stations from Gulf Broadcast Co., a Dallas firm hotly pursued since it was put on the block last month. The properties include an FM radio station in Washington.

Analysts expressed surprise about the proposed buyout of Multimedia, a diversified communications firm based in Greenville, S.C. The bidders include Multimedia's senior executives, members of its founding families and a private investor group to be organized by investment banker Goldman, Sachs & Co.

In a telephone interview, Walter E. Bartlett, Multimedia president and a member of the investment group, said the offer was being made for investment reasons.

The insiders currently own about 40 percent of Multimedia's 16.7 million shares outstanding. After the buyout, insiders would own "a little more than 40 percent," Bartlett said.

The group is offering $37 cash and $25 principal amount of 20-year subordinated discount debentures for each Multimedia share. Because the debentures will bear no interest for five years, some analysts discounted their market value to about $13. At that value, the offer would be about $50 a share.

Multimedia owns 13 daily and 30 nondaily newspapers; 5 television and 12 radio stations; cable-TV systems in four states; and 5 percent of the Cincinnati Reds professional baseball team. It also produces such syndicated television programs as the Phil Donahue show.

Cincinnati-based Taft said it has agreed to acquire TV stations in Phoenix; Dallas; Houston; Tampa-St. Petersburg; and the Greensboro-Winston-Salem, N.C., area. It also has agreed to buy FM radio stations in Dallas, Houston and Washington, and AM-FM combinations in Atlanta and Indianapolis.