Kyle Leighton says the above chart explains Obama's comeback:
The short-lived bump from the killing of Osama bin Laden was countered by a strong trend downward toward the politically poisonous summertime fight with Congressional Republicans over raising the debt ceiling. No one got out of that one unscathed — but, there was ample evidence that the GOP hobbled itself even more going into an election cycle when they were supposed to have the upper hand, with more voters blaming them for the sorry affair than Democrats. After a debt agreement was done, Obama immediately made a successful pivot to jobs, and the public responded. … Those factors led to an uptick over the last three months, just as the Republican presidential primary process began in earnest.
Joe Weisenthal and Jon Terbush offer a different interpretation:
Obama's approval rating comes down basically to one thing: The stock market. The below chart takes a weekly look at his approval rating done by Gallup vs. the daily level of the S&P 500. The lines basically move together perfectly. THIS is why the President is coming back.