The 5-0 decision by the FTC represented the most significant regulatory hurdle yet to AOL and Time Warner in their nearly year-long attempt at obtaining approval for their business combination, one of the largest in corporate history.
AOL shares opened at $48, down from Wednesday's close of $48.45. But after the approval was announced, the stock bumped up $1.55 to close at $50. The shares have traded within a range of $37 to $95.81 during the past 52 weeks.
Time Warner also opened slightly lower than its Wednesday close of $72.60. Shares in the media giant gained $1.90 to close at $74.50. The stock has wavered between $57.51 and $105.50 during the past year.
Since the merger was announced Jan. 10, shares of AOL have tumbled 33 percent, sliding with the broad sell-off in tech shares. Time Warner shares, however, have climbed about 14 percent.
The decline in AOL shares has reduced the combined financial heft of the company.
Based on their market capitalizations at the time of the announcement, a combined AOL Time Warner would have had a value of about $350 billion. Today, the combined company will be worth closer to $214 billion, with AOL's market value at $116 billion and Time Warner's at $98 billion.
Under the deal, Time Warner shareholders will receive 1.5 shares in the combined company for each share they hold, while AOL shareholders will receive one share.
Rivals such as Walt Disney, contending that the merger will create an unfair media monopoly, have heavily lobbied government regulators to reject the deal or impose significant restrictions. The merger still faces review by the Federal Communications Commission.
Disney shares closed down 75 cents at $29, well below their 52-week high of $43.87.