Headwaters, Presstek, Pioneer Natural, Zoran: U.S. Equity Movers

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.

Chipmakers dropped after Wells Fargo & Co. said the industry’s inventory rose during the first quarter and memory prices continued to fall last week. Intel Corp. (INTC US) fell the most in the Dow Jones Industrial Average, sliding 2.1 percent to $22.76. Micron Technology Inc. (MU US) sank 3.8 percent to $10.46.

Oil companies rallied as the price of oil climbed above $102 a barrel, rebounding from the biggest weekly decline since

2008. Pioneer Natural Resources Co. (PXD US) climbed 5.4 percent to $93.92. Marathon Oil Corp. (MRO US) increased 5.3 percent to $52.19, while Baker Hughes Inc. (BHI US) added 3.4 percent to $71.65.

Dollar Thrifty Automotive Group Inc. (DTG US) jumped 14 percent to $79.27, the highest price since it went public in December 1997. Hertz Global Holdings Inc. (HTZ US), the largest publicly traded rental-car company, offered to buy Dollar Thrifty, countering a bid by competitor Avis Budget Group Inc. (CAR US). Hertz offered $72 a share in cash and stock for Dollar Thrifty, 24 percent more than Avis’s offer and 18 percent higher than the 60-day average share price.

Gaiam Inc. (GAIA US) rose 14 percent, the most since April 2009, to $5.83. The provider of health and fitness products is scheduled to announce its first-quarter results after the market close. Two analysts surveyed by Bloomberg estimated a loss of 2 cents a share, on average.

H&R Block Inc. (HRB US) slipped 7.6 percent to $15.93 for the biggest decline in the Standard & Poor’s 500 Index. A group of mortgage-bond investors is seeking to force the tax preparer’s Option One Mortgage Corp. unit to repurchase soured loans. Talcott Franklin PC is asking investors to submit their voting rights in favor of seeking recoveries on loans that were sold in violation of contracts, the Dallas-based law firm said in an e-mailed statement.

Headwaters Inc. (HW US) slumped 18 percent to $4.01, the biggest decline in the Russell 2000 Index. The coal-mining services provider reported a second-quarter adjusted loss of $1.21 a share, wider than the 34-cent loss that was the average of analyst estimates.

Nuance Communications Inc. (NUAN US) increased 8.3 percent to $21.76, the highest price since December 2007. The U.S. maker of speech-recognition software has been in talks with Apple Inc. in recent months for a possible partnership or acquisition, according to TechCrunch, which cited unidentified people.

Oncothyreon Inc. (ONTY US) advanced 11 percent, the most since Dec. 22, to $4.97. The developer of cancer treatments reported a first-quarter loss excluding some items of 19 cents a share, more than the 18-cent loss predicted by analysts on average.

PetMed Express Inc. (PETS US) declined 11 percent, the most since January 2007, to $13.14. The seller of pet drugs and vitamins reported fourth-quarter earnings of 19 cents a share, trailing the average analyst estimate of 22 cents in a Bloomberg survey.

Presstek Inc. (PRST US) surged 16 percent, the most since March 9, to $1.84. The developer of non-photographic digital imaging reported first-quarter revenue of $31.9 million, beating the $31 million estimated by one analyst.

Rosetta Resources Inc. (ROSE US) gained 20 percent, the most since May 2009, to $49.48. The oil and natural gas company reported first-quarter sales that topped analysts’ estimates. Capital One Southcoast Inc. and raised the stock’s rating to “add” from “neutral” while Tudor Pickering & Co. upgraded the shares to “hold” from “trim.”

Sysco Corp. (SYY US) rose the most in the S&P 500, soaring 11 percent to $31.57. North America’s largest distributor of food to restaurants, hospitals and schools reported third-quarter adjusted profit of 46 cents a share on sales of $9.76 billion, beating analysts’ estimates.

Tyson Foods Inc. (TSN US) fell 6 percent to $17.75 for the second-biggest retreat in the S&P 500. The largest U.S. meat processor reported second-quarter earnings excluding certain items that missed the average analyst estimate by 4.3 percent.

Zoran Corp. (ZRAN US) fell 10 percent, the most since Oct. 26, to $8.58. The maker of chips for digital audio and video products, which is merging with CSR Plc (CSR LN), reported a first-quarter loss of 43 cents a share, missing the average analyst estimate by 14 percent, according to Bloomberg data. CSR, a maker of chips used in Nokia Oyj mobile phones, said it is considering the implications of Zoran’s earnings statement.

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