In 2009, Zynga was a marquee customer for Amazon.com 's cloud-computing services. Two years later, it spent $100 million to build its own data centers to handle the bulk of its computing. Now Zynga's cloud cruise has come full circle.

The company Wednesday said it would shut its data centers and shift its computing workload back to Amazon, as part of $100 million in spending reductions.

"There's a lot of places that are not strategic for us to have scale and we think not appropriate, like running our own data centers," Zynga CEO Mark Pincus told investors on a conference call. "We're going to let Amazon do that.”

Why the change? Well, Zynga's business changed. The company grew fast as a maker of popular Web-based Facebook apps, but stumbled as the world moved to mobile games.

"Their business didn't grow the way they expected," said Lydia Leong, an analyst with industry research firm Gartner. "Games were unpredictable,” she said, making it hard to plan computing needs.