There's been a lot of uproar about the Federal Reserve possibily tapering its bond-buying program.

Some have attributed the risk of the Fed taper to the return of volatility in the stock markets, but this volatility may be explained more directly by a larger reason: deteriorating earnings expectations.

"[E]arnings matter the most for equities, in our opinion, and there is relatively robust statistical evidence to back up that contention," said Citi's Tobias Levkovich.