Yahoo! ( YHOO) rose $2.61, or 12.2%, to $23.96 after activist investor Carl Icahn revived hopes of a Microsoft buyout deal for Yahoo!.

Icahn said he has been in talks for the past week with Microsoft CEO Steve Ballmer, noting Ballmer would be interested in restarting negotiations if shareholders elected Icahn's slate of directors to the board at Yahoo's upcoming shareholder meeting in early August. Yahoo has been under intense pressure from shareholders after it rejected Microsoft's $31 a share offer for the company a few weeks ago.

Fannie Mae ( FNM) and Freddie Mac ( FRE) were tumbling more than 20% at one point after an analyst at Lehman Brothers expressed worries about new accounting requirements that might force both government-formed companies to raise billions of dollars in new capital.

Chipmaker Broadcom ( BRCM) was up $1.88, or 7.2%, to $28.10 in part because of positive research notes from Wall Street analysts. An analyst at Piper Jaffray upgraded the stock to buy from hold, saying investors are underestimating the revenue potential for a few product cycles.

Potential sources of revenue upside include a "key design win" for Nokia's videocore processor, the 3G iPhone for which Broadcom supplies a chip, the migration to high definition video and its impact on Broadcom's sales of set-top boxes and Blu-ray player chips, the analyst said.

A Goldman Sachs analyst also named Broadcom as one of the chip makers most likely to benefit from the strong demand for the 3G iPhone.

Radian ( RDN) skyrocketed 70% before settling down to a gain of 51.9%. Last Thursday, the insurer announced that it paid out less in claims during the second quarter than expected and on Monday it named a new head of its mortgage unit.

The Philadelphia-based firm was trading at $1.55, a gain of 53 cents. Similarly, PMI Group ( PMI) jumped 7.4% to $1.59 as investors hoped to hear that it too, was able to contain its payouts.

Teva ( TEVA) skidded after the company said that according to top-line results of a trial dubbed "FORTE" the higher, 40mg dose of Copaxone was no more effective than the already FDA-approved 20mg dose in relapsing-remitting multiple sclerosis (RRMS).

Teva shares fell $4.54, or 9.6%, to $42.66.

APP Pharmaceuticals ( APPX) rocketed $5.27, or 30%, to $23.09 after German health care company Frenenius said it will buy the Schaumburg, Ill., drugmaker for $3.7 billion, or roughly $23 a share, a 29% premium to APP's closing price on Thursday.

Internet Gold-Golden Lines ( IGLD) was up 17.9%, or $1.17, to $7.72 after announcing plans to repurchase $21 million of stock. Internet Gold-Golden Lines is an Israel-based company focused on offering broadband data and traditional voice services to residential and business customers, as well as to other Israeli and international communication services providers.

Interactive Intelligence International ( ININ) was losing ground today as management sees second-quarter estimates coming in below consensus. Management expects earnings of 12 cents to 14 cents a share, compared with the mean Thomson Reuters estimate of 17 cents. Interactive Intelligence moved down 25.6%, or $2.68, to $7.78. The Indianapolis-based company provides software applications for contact centers and voice over Internet protocol applications to enterprises.
This article was written by a staff member of TheStreet.com.