"Our price target is based on two things: It's a model of earnings and a model of the multiple," she said. "The multiple, obviously, has been tremendously difficult to predict because of the evolution of Fed policy over the last several years. The earnings numbers are actually tracking about as we expected."
Adams held a 1,390 price target in the S&P 500 for the end of 2013. It traded at 1,671 at 1 p.m. ET.
(Read More: What to Make of Goldman's Bullish S&P 500 Call)
On CNBC's "Fast Money," Adams acknowledged that stock valuation multiples had been "running ahead of our expectations."
"It remains to be seen whether we'll get that multiple contraction into the second half of this year, resulting in lower equity prices, ultimately," she added.
Adams also said that her outlook might be more bearish than necessary for now.
(Read More: It's Time to Play Defense: Gina Martin Adams)
"You can underestimate on the upside. We're probably overestimating on the down side," she said. "It's the nature of the equity markets to overreact in both directions. I think the mantra, 'Don't fight the Fed,' works both ways. You don't fight the Fed on the way up, but you also don't fight the Fed on the way down."
(Read More: Market Gains Could Keep on Coming After Dow 15,000)
Trader disclosure: On May 21, 2013, the following stocks and commodities mentioned or intended to be mentioned on CNBC's "Fast Money" were owned by the "Fast Money" traders: Joe Terranova is long VRTS ; Joe Terranova is long SJM; Joe Terranova is long SPLK; Joe Terranova is long LNKD; Joe Terranova is long TBT; Joe Terranova is long SWN; Stephen Weiss has nothing to disclose; Josh Brown has nothing to disclose.