Sun Microsystems agreed to buy Storage Technology Corp. for $4.1 billion to add machines that store and retrieve data. Storage Technology investors will receive $37 a share in cash, Santa Clara, California-based Sun said in a statement today. That represents an 18 percent premium over yesterday's closing stock price. The purchase will step up competition with International Business Machines Corp. and storage companies such as EMC Corp. as Sun Chief Executive Scott McNealy seeks to regain market share and stem losses. The combined company will have more than $13 billion in annual revenue. Sun rose 11 cents, or 2.8 percent, to $4.01 in Nasdaq Stock Market composite trading. They had dropped 28 percent this year before today. McNealy has changed top executives, fired employees and shuttered facilities to narrow its losses, which totaled $4.4 billion from 2002 to 2004. The company is shifting from relying on higher-priced servers to clusters and Grids. The purchase of Louisville, Colorado-based Storage Technology will add to profit, excluding some costs, in the first 12 months after the closing, Sun said.