Shares of the following companies had unusual moves in U.S. trading. Stock symbols are in parentheses, and prices are as of 4 p.m. in New York.

Barnes & Noble Inc. (BKS) surged 52 percent to $20.75 for the biggest increase in the Russell 2000 Index and the stock’s best ever gain. A new subsidiary that combines the bookseller’s Nook digital reader and college businesses will receive a $300 million investment from Microsoft Corp. (MSFT US).

Conceptus Inc. (CPTS) rose 24 percent, the most since October 2008, to $18.77. The maker of a female-sterilization method boosted its full-year sales forecast.

Demand Media Inc. (DMD) rallied 15 percent to $8.31, the highest price since Sept. 27. A deal by Thomas H. Lee Partners to take private the operator of websites eHow.com and LiveStrong.com for $1.2 billion fell apart, AllThingsD said, without saying where it got the information.

Expedia Inc. (EXPE) gained 5.8 percent to $42.65, the highest price since at least 2005. The online-travel company rallied for a second day after saying on April 26 that first- quarter profit and revenue topped analysts’ estimates, driven by growth in the Hotels.com unit.

Gen-Probe Inc. (GPRO) climbed 19 percent, the most since April 2003, to $81.55. The developer of testing for sexually transmitted disease agreed to be bought by Hologic Inc. (HOLX) for about $3.7 billion in cash. Hologic slipped 9.9 percent to $19.12.

Harman International Industries Inc. (HAR) increased 4.9 percent, the most since Dec. 20, to $49.58. The maker of audio equipment for cars and homes reported third-quarter earnings excluding some items of 74 cents a share, exceeding the average analyst estimate of 67 cents.

Humana Inc. (HUM) declined 8.1 percent, the most in the S&P 500, to $80.68. The second-biggest provider of U.S.-backed Medicare insurance said first-quarter profit declined as premiums failed to keep up with rising medical costs.

Imperial Holdings Inc. (IFT) surged 30 percent, the most since it went public in February 2011, to $3.83. The specialty finance company agreed to pay an $8 million penalty to resolve fraud allegations related to its involvement in making misrepresentations on life insurance applications, the Department of Justice said.

NYSE Euronext (NYX) had the second-biggest decline in the S&P 500, retreating 4.9 percent to $25.75. The largest U.S. exchange operator reported a 44 percent decline in first-quarter profit, as expenses related to its failed merger with Deutsche Boerse AG combined with a slowdown in trading.

Sohu.com Inc. (SOHU) dropped 7.5 percent, the most since Feb. 6, to $51.57. The operator of China’s third-biggest online video site forecast lower-than-expected growth in revenue this quarter as an economic slowdown weakened online advertising sales.

Sunoco Inc. (SUN) climbed 20 percent to $49.29 for the biggest advance in the S&P 500. The Philadelphia-based refiner agreed to be acquired for $5.3 billion in shares and cash by Energy Transfer Partners LP (ETP US), which is adding oil transportation and distribution assets.

TeleCommunication Systems Inc. (TSYS) slipped 8.5 percent to $1.93, the lowest price since June 2003. The Annapolis, Maryland-based network applications company was cut to underperform from sector perform at RBC Capital Markets.

Tenneco Inc. (TEN) fell 15 percent, the most since Aug. 8, to $30.83. The world’s largest maker of vehicle-exhaust systems reported first-quarter earnings and revenue that fell short of the average analyst estimates.

VeriFone Systems Inc. (PAY) slipped 12 percent, the most since March 2009, to $47.64. The largest maker of credit-card terminals was cut to sell from hold by Deutsche Bank AG.

Warner Chilcott Plc (WCRX) gained 16 percent, the most since August 2009, to $21.81. The maker of dermatology and women’s health drugs said it is exploring a sale of the company and is in talks with potential buyers.

To contact the reporter on this story: Whitney Kisling in New York at wkisling@bloomberg.net

To contact the editor responsible for this story: Michael P. Regan at mregan12@bloomberg.net