SAN FRANCISCO — Notching another conquest in its push to create a one-stop shop for business software, Oracle Corp. is snapping up rival BEA Systems Inc. for $8.5 billion in a deal culminated after several months of acrimony.

The acquisition announced Wednesday extends a three-year spree in which Oracle has spent about $35 billion buying dozens of its smaller competitors.

San Jose-based BEA represents Oracle's most expensive purchase since it paid $11.1 billion for PeopleSoft Inc. in early 2005. Part of Oracle's expense will be offset by $1.3 billion in cash that it expects to inherit from BEA after the marriage is consummated later this year.

The all-cash price of $19.375 per share represents a 24 percent premium from BEA's closing stock price Tuesday. It's 42 percent improvement from where BEA's shares stood before Oracle launched an unsolicited bid of $17 per share that was rebuffed almost three months ago.

Oracle's dogged pursuit of BEA underscores how much it prizes BEA's so-called "middleware" — computer coding that helps business programs run more smoothly on underlying databases.

Already entrenched as the leader in the database market, Oracle, based in Redwood Shores, Calif., in recent years has been building up an array of business applications software to challenge the front-runner in that segment, Germany-based SAP.

BEA's products, already used by about 15,000 customers, will give Oracle another potential selling point with companies looking for a suite of software from a single vendor in an effort to make their technology run more smoothly.