The financial bailout, but just barely.
Financial bailout: $700 billion.
Lost productivity due to multitasking: $650 billion per year.
That number is from The Myth of Multitasking: How “Doing It All” Gets Nothing Done:
2.1 hours: Average estimated lost productivity per person per day due to interruptions, based on a 40-hour work week.
$650 billion: Estimated annual loss to the US economy due to unnecessary interruptions plus recovery time.
If you move beyond the time frame of a single year, however, you see that multitasking is actually far, far more expensive than the financial bailout.
For the financial bailout was a one-time thing. Multitasking costs $650 billion every single year. So, after ten years, we have this:
Financial bailout: $700 billion
Multitasking: $6.5 trillion
Even if a second bailout were necessary, or the cost of the bailout went up, the cost of multitasking still far outstrips the potential cost of the bailout over a ten year period.
Add to this the fact that the bailout probably prevented damage to the economy that far exceeded $700 billion (I realize that there is difference of opinion there), and you have even less of a contest.