Citi's Matt King highlights the key issue for the Fed right now as it explicitly pushes up asset prices: "When falling short on your inflation and employment benchmarks, does creating asset price bubbles improve your chances of hitting your targets, or detract from them?"

He's relatively bearish on corporate fundamentals, but recognizes that's not what's driving markets. "Trying to time a market bubble wouldn’t normally be a good idea. But the near-explicit endorsement of the price action by the Fed leaves investors with little choice."

The research note is called "Timing the market top" and is a really compelling and persuasive piece.