Riverbed Technology (RVBD)

WITH ACQUISITION OF MAZU NETWORKS

Powerful and Flexible Software Delivers Visibility, Reporting and Analytics for Enterprise and

Service Provider Customers

SAN FRANCISCO – January 20, 2009 – Riverbed Technology (NASDAQ: RVBD) today announced it has agreed to acquire Mazu Networks, a privately-owned company that helps organizations manage, secure and optimize the availability and performance of global applications. The Mazu organization, based in Cambridge, Massachusetts, will become a business unit of Riverbed. In connection with the acquisition of all of the outstanding securities of Mazu, Riverbed will pay approximately $25 million in cash at closing, with an additional possible payment based on future sales performance.

Mazu Networks provides a unique, powerful and flexible analysis and reporting software that provides a holistic, real-time view of application usage and performance. This perspective is critical to understanding the application environment and taking the right steps to validate and ensure delivery of business-critical applications across the wide area network (WAN).

“The market for WAN optimization is fast becoming more mainstream and increasingly our enterprise and service provider customers are demanding more visibility, reporting and analytics capabilities from us as they seek to deploy more robust infrastructure for managing their global applications,” said Jerry M. Kennelly, president and CEO of Riverbed. “This requirement is driven by the enterprise’s need to reduce costs via consolidation, improve end-user productivity, and leverage technology to streamline business processes.”

The acquisition of Mazu Networks allows Riverbed to meet enterprise and service provider customer demands by extending its suite of WAN optimization products to include global application performance, reporting and analytics. This provides customers with a closed-loop system for managing enterprise-wide applications by intelligently monitoring and analyzing performance, demonstrating the need for return on investment (ROI) of optimization, and allowing users to continuously manage performance targets to predetermined objectives.

“Our service provider customers require an integrated system to monitor and deliver a managed WAN optimization service,” continued Kennelly. “By providing an integrated solution based on

Mazu’s market-leading offerings, we are able to tailor the reporting to demonstrate the value of optimization, which in turn supports the value of the provider’s service to its customers.”

Riverbed has become the leading IT infrastructure performance company by delivering the benefits of speed, scale, and simplicity to thousands of customers around the world, and WAN optimization will continue to be the primary driver of Riverbed’s ongoing success. The Mazu product line supports Riverbed’s position by delivering speed in performance analysis, providing scale to Riverbed’s customers’ ability to monitor the optimization and performance of their key applications and allowing Riverbed to deliver simplicity in the analysis and reporting of that information across a customer’s entire environment with customizable dashboards and reports.

Key Financial and Other Terms of the Transaction:

Conference Call Information

Riverbed will host a conference call today, Tuesday, January 20, at 2:30 p.m. Pacific Time to discuss the acquisition. To participate in this conference call, please call (866) 582-1076 or (706) 634–6541, password “Riverbed”. A simultaneous audio webcast of the conference call will be available at www.riverbed.com/investors and archived on the Riverbed website for three months. In addition, a telephone replay will be available today by 6 p.m. Pacific Time through the end of day Friday, January 23, 2009. To access the telephone replay, dial (800) 642-1687 or (706) 645-9291, conference ID # 81607527.