San Francisco-based Riverbed Technology, which develops WAN optimization and network management products, said today that it has acquired OPNET Technologies, a provider of application and network performance management products. The deal is worth approximately $1 billion, or $43 per share in cash and stock for each share of OPNET, and has an enterprise value of $921M. Riverbed said the buy will bring the firm to over $250M in annualized revenue. Riverbed was advised by Goldman, Sachs &. Co, Weil, Gotshal & Manges LLP and Wilson Sonsini Goodrich & Rosati in the deal; OPNET was advised by Lazard, and Cooley LLP.