Motorola reduced quarterly guidance on Wednesday evening, buttressing activist investors' recent demands for a management shakeup, only hours after rumors of a change at the top sent the shares higher.

Attributing the expected shortfall to lower mobile device shipments in Europe and Asia, the cell phone maker said in a release that it now expects a second-quarter loss of 2 to 4 cents a share, on a GAAP basis, compared with previous expectations for a profit of 3 to 4 cents a share.