The stock market has powered ahead of the nation's faltering economy so far in 2013 at the same time that the Federal Reserve keeps supporting U.S. Treasuries by keeping interest rates low.

These seemingly contrary events have left investors so uncertain about what will happen next that BlackRock, the world's largest asset manager, with $3.79 trillion under management as of Dec. 31, has stepped forward to offer three actions for worried investors to take.

"The powerful advance of U.S. stock markets has investors asking: Do the markets have more room to run, or is a correction imminent? First, we think there is almost no chance that the pace seen in the first quarter will continue. But does that mean we're in the middle of a bubble that will burst? The answer is no," write Russ Koesterich (left), BlackRock chief investment strategist and iShares chief global strategist, Jeffrey Rosenberg, chief investment strategist for fixed income, and Peter Hayes, head of the municipal bonds group.