Shares of Houston Exploration ( THX) were among the NYSE's winners Monday, rising 8% after hedge fund Jana Partners offered to buy the oil exploration company for $62 a share in cash.

Jana, which owns 12.3% of Houston Exploration, said that it believes there is "tremendous value" in the company, but that the value would be "destroyed" if the company continues to remain in the hands of current management. "Particularly given the board's recent confirmation that it intends to proceed blindly ahead with demonstrably wasteful acquisitions despite the shareholder outcry this has generated, we believe action must be taken now to protect the value of our investment in the company," Jana said in a press release. Jana, which has previously called on Houston Exploration to enact a $650 million share repurchase plan and seek strategic alternatives, requested that Houston Exploration open discussions with the hedge fund immediately. Shares of Houston Exploration recently were trading up $4.11 to $58.76.

Teekay Shipping ( TK - Get Report) jumped 6% after the tanker operator said it plans to create a new publicly traded partnership that will cater to the offshore energy sector. The limited partnership will be called Teekay Offshore Partners. "We have been evaluating strategic initiatives for our offshore services business particularly at a time when offshore oil exploration and production is expected to grow significantly," the company said. Teekay said it expects to file a registration statement for the initial public offering during the second half of 2006.

Separately, Teekay said its board increased its share repurchase plan by $150 million. Coupled with the $36 million that still remained under its previous buyback plan, the company will now be able to buy about $186 million in stock. Since the end of November 2004, the company has repurchased some $747 million in stock, representing about 21.3% of its outstanding shares. The shares were trading up $2.05 to $39.18.

Shares of Zale ( ZLC) surged 13% after British jewelry retailer Signet said it has preliminary discussions with the company regarding a possible merger. In a brief statement, Signet said there is "considerable uncertainty" as to whether any transaction will occur. Shares of Zale were trading at $26.88, up $3.01.

Shares of Hansen Natural ( HANS) rose 2% after the beverage maker set plans for a 4-for-1 stock split. The shares will be distributed on or after July 7 to shareholders of record on June 30. "The board's action conveys its confidence in the long-term prospects for Hansen," the company said. "Additionally, we hope this will improve the company's stock liquidity and decrease its volatility in the marketplace as a result of the increase in the number of shares outstanding." Shares, which have more then doubled since the beginning of the year, recently were trading up $3.34 to $169.10.

Shares of NRG Energy ( NRG - Get Report) slid 7% after Mirant ( MIR) withdrew its $8 billion bid for the company. Mirant said it withdrew the offer after it became clear that NRG would not allow itself to be acquired without a drawn-out fight. "We are disappointed that NRG was unwilling to sit down with us to discuss what would have been a compelling opportunity to create significant value for both companies' shareholders," Mirant said in a press release.

NRG, for its part, suggested that it is better off without the merger. "Over the past 24 months, NRG's stock has appreciated 120% as the market has recognized the value of our asset mix, the soundness of our strategy and our history of returning capital to shareholders," NRG said. "We are poised for further value creation and look forward to the continued execution of our strategic plan." Shares of NRG were trading down $3.52 to $47.33, while shares of Mirant gained 40 cents to $24.85.

Pacer International ( PACR) rose 3% after the logistics and transportation provider announced a $60 million stock buyback plan. The share repurchase plan expires on June 15, 2008. Shares were up 73 cents to $29.96.

NYSE volume leaders included Disney ( DIS - Get Report), down 87 cents to $28.46; Motorola ( MOT), up 5 cents to $20.64; Corning ( GLW), down $1.26 to $21.01; Lucent Technologies ( LU), down 2 cents to $2.43; Texas Instruments ( TXN), down 23 cents to $29.45; Nortel Networks ( NT), up 2 cents to $2.23; Ford ( F), up 14 cents to $6.90; General Motors ( GE), up 66 cents to $26.01; and Pfizer ( PFE), up 5 cents to $23.58.

Nasdaq volume leaders included JDSU ( JDSU), down 15 cents to $2.58; Level 3 Communications ( LVLT), down 23 cents to $4.25; Microsoft ( MSFT), up 13 cents to $22.05; Intel ( INTC), up 5 cents to $17.21; Sirius Satellite Radio ( SIRI), down 5 cents to $4.21; Broadcom ( BRCM), up 62 cents to $29.95; Pozen ( POZN), up 55 cents to $6.07; and Apple Computer ( AAPL), down 50 cents to $58.74.