Half-a-dozen years ago, East Ventura County’s economy was heavily dependent on two very large employers: subprime lending giant Countrywide Financial Corp. and biotech behemoth Amgen.

Each had more than 5,000 workers, creating a highly concentrated mega-employer effect on housing, shopping and services. Today, Countrywide is part of Bank of America and has a much-reduced staff in the region. And Amgen’s retrenchment entered a new phase on July 29, when it said it will shed between 2,400 and 2,900 jobs around the world, close plants in Colorado and Washington state, and shrink its Conejo Valley presence.

Countrywide’s locations included a Simi Valley loan processing center and executive offices that sprawled along Highway 101 in the Thousand Oaks to the Calabasas area.

Amgen’s campus is a highly concentrated collection of some 40 buildings in the Newbury Park area of Thousand Oaks. The biotech firm, the world’s largest by revenue, employs thousands of scientists in Ventura County. Over the years, its corporate headquarters staff has grown with the company’s market capitalization, which is now approaching $100 billion.

Coming on the heels of earlier layoffs, Amgen’s announcement makes it clear that while it may well remain the biggest corporate employer in Ventura County, the days in which it will dominate the Conejo Valley economy gradually are coming to an end.

What does the future hold? First, the skill sets that have been created in mortgage servicing and advanced production in biologics are attractive. The core Amgen manufacturing operations are extremely difficult to replicate. We’ll take the company at its word that its corporate flag is likely to remain in Thousand Oaks for the foreseeable future.

Second, the spinoff effects from Amgen and Countrywide are likely to be long lasting.

Former Countrywide executives have created mortgage firm PennyMac, which has hired 1,000 people in Moorpark, not far from the former Countrywide digs. Amgen’s spinoff effect has been slower to come, partly because the epicenters for drug development have shifted to the Bay Area, San Diego and Cambridge, Massachusetts. Nonetheless, we have already seen a number of promising Amgen spinouts in East Ventura County, including Atara Biotherapeutics and ImmunGene, two Thousand Oaks firms that have each attracted millions of dollars in venture capital.

Finally, a more diversified economy will give East Ventura County a more stable future. With good schools, a variety of housing options and low crime rates, it will remain attractive for the next generation of employers.