Shares of memory chip developer Rambus Inc rose 8 percent on Friday on speculation that Samsung Electronics would buy the company, but Samsung said it had no such plans.

Rambus shares rose as much as 14 percent to $18.15 on the Nasdaq and its options traded briskly on talk that Samsung could pay $25 to $27.50 per share.

Rambus shares gave up some of those gains after Samsung issued a denial, trading at $17.44 Friday afternoon.

Rambus declined to comment.

We've heard this rumor before. I don't find it likely, said Capstone Investments analyst Jeff Schreiner, who noted that a Rambus poison pill provision would protect the company from any hostile takeover lower than $60 a share.

On Thursday, Samsung said it had definitely dropped its previous efforts to buy another memory chip maker, SanDisk Corp, for $5.9 billion. South Korea's Samsung cited SanDisk's deepening losses and uncertain outlook for dropping the offer.

Samsung is one of several companies facing an antitrust case from Rambus, which has made accusations about price-fixing and hurting sales of its RDRAM memory chips used in computers. That case is expected to be heard next year.

Schreiner said a Samsung-Rambus merger would have its own antitrust ramifications because Samsung is the leader in the market for DRAM chips.

While Schreiner said he heard speculation of a price tag of $27.50 per share, Jon Najarian, a founder of optionMonster.com, cited rumors of a deal worth $25 to $27.

Najarian said rumors were common in the options market, but added there were very fast trades in Rambus front month September call options, notably the $17, $18, $19 and $20 strikes.

These options are being aggressively bought on the offer, he said.

About 56,000 call options traded in Rambus, more than twice its average daily turnover, according to option analytics firm Trade Alert.

(Reporting by Sinead Carew and Ritsuko Ando in New York, and Doris Frankel in Chicago; Editing by Steve Orlofsky, Leslie Gevirtz)

South Korea Electronics Samsung