AOL announced a $600 million accelerated stock buyback plan and a special cash dividend of $5.15 a share, final steps in returning about $1.1 billion to shareholders. AOL will buy common stock under a deal with Barclays. The dividend will be payable Dec. 14. AOL, owner of the Huffington Post and TechCrunch websites, rose this month to its highest value since it was spun out of Time Warner Inc. in 2009.