Synchronoss to buy back $25 million of its shares

As of Feb. 15, the company had about 32.7 million outstanding shares, according to a regulatory filing.

Separately, Synchronoss reported its first-quarter results and said it "materially" lowered its 2008 growth expectations as it expects its largest customer to contribute less to total sales.

Shares tumbled $10.08, or 44 percent, to $12.82 in after-hours electronic trading. The stock earlier closed down 5 cents at $22.90. Shares have traded in a 52-week range of $15.15 to $48.03.