HBK Investments urged the electronics retailer to allow due diligence by Blockbuster (ticker: BBI), following the video chain's acquisition proposal. The hedge fund also urged Circuit City's board to create a competitive bidding process in order to maximize shareholder value, saying the firm itself might be prepared to offer financing for a Blockbuster purchase. HBK reported holding about 15.42 million shares (9.1% of the total outstanding). HBK's funds also own about 8% of Blockbuster's Class A stock and roughly 5% of its Class B shares.

Hedge-fund manager Steven A. Cohen suggested a sale of the life-science research company. Cohen said his SAC Capital Advisors sent a letter last month to the non-management directors of Applera, the parent of Applied Biosystems, expressing its continued support for the recent spinoff of Applera's Celera Group (CRA) as an independent entity. He also encouraged Applera's board to take a number of actions. Among them, SAC Capital asked Applera to explore all strategic alternatives, including the sale of the Applied Biosystems Group. SAC Capital holds 8,604,018 shares (5.1%).

Alpine Associates, a limited partnership, sent a letter to the oil and natural gas drill-rig company opposing its proposed sale to Allis-Chalmers Energy (ALY). Alpine said that circumstances have changed dramatically since this transaction was announced four months ago, and that it believes Allis-Chalmers' $16.33 a share offer is inadequate. It wants a significant improvement in the terms. Alpine owns about 1.6 million shares (6.1%).

In a letter to the biotech company's board, DellaCamera Capital Master Fund said it's unhappy with the compensation granted to Enzon Chairman and CEO Jeffrey Buchalter. The hedge fund also noted that it's reviewing its voting alternatives on three directors up for election at the company's May 22 annual meeting of shareholders. DellaCamera further called for the resignation of Goran A. Ando, Rolf A. Classon and Victor P. Micati, all members of Enzon's compensation committee. DellaCamera holds 2,579,127 shares (5.8%).

ValueAct Capital Management reported ownership of 2,511,552 shares (6.7%) after buying those shares from March 11 to April 23 at $11.56 to $12.99 each.

A group including Elkhorn Partners raised it stake to 1,529,200 shares (5.7%) after buying 188,000 shares for $3.84 to $4.40 a share during the last 60 days.

Chapman Capital cut its holdings to 329,296 shares (6.3%) from the 395,302 (7.6%) reported in July 2007.

Chapman Capital lowered its stake to 13 million shares (5.8%) from the 15.6 million (7%) reported in December 2007.