ICI sees things differently. Antoniewicz pointed out January is historically a strong month for inflows as investors make their annual contributions to IRAs and year-end bonuses are invested. This year, fund inflows got another leg up from investors deploying cash raised from selling investments at year end, to avoid paying higher taxes in the New Year, she said. This suggested a bulge in the fund inflows that may not be sustained, a theory supported by the weekly fund flow data from ICI.
Net inflows into domestic equity mutual funds fell 54 percent from over $7.7 billion in the week ended January 9, to $3.4 billion in the week ended January 23, suggesting the New Year's surge is fading fast.
A better read on retail interest in the stock market would be sustained inflows into equity funds and ETFs, said Antoniewicz. She noted if you see inflows remain strong through the first quarter and into April, you could make a better case for the retail investor's being back.
Still, the retail investor, or at least mutual fund flows, may be becoming less of a factor in driving the stock market to new heights.
"When the markets rise we typically see mutual fund flows rise," said Antoniewicz. "That said we've seen a weakening of that relationship over the last three or four years." (Read more:
Why This Market Correction May Have a Way to Go
She cited a number of reasons for this disconnect between fund flows and market performance. First, as Baby Boomers age, they put less money at risk and therefore less money in the stock market. (Read More: Well-Off Show 'Worrisome Disconnect' on Retirement)
Second, perhaps reflecting investors recent experiences with stock market booms and busts, there is a trend toward more diversified portfolios and funds that are not pure play stock funds. Lastly, mutual funds are no longer the only way to gauge the interest of the retail investor as more of them are using alternative investments like ETFs or exchange traded funds.
—By CNBC's Mary Thompson; Follow her on Twitter: