After spending much of this year explaining why its two businesses are best left together, eBay's board of directors and CEO did a complete about-face Tuesday morning, announcing a plan under which its PayPal and eBay marketplace businesses will be split into separately traded public companies by the middle of next year. And CEO John Donahoe will step down as CEO of eBay once the split takes effect in 2015.

EBay shares jumped on the news, rising by more than 7 percent by midday. They were on pace for their best day since July 19, 2012, when they rose 8.6 percent. (Get the latest quote here.)