A market signal with a nearly perfect track record points to a strong year for stocks, according to S&P Dow Jones Indices.

"Since 1938, there's been 30 years where both January and February have been positive. And 29 of those years out of 30 have ended up positive, and big, on average over 20 percent," Jodie Gunzberg, head of U.S. equities at S&P Dow Jones Indices, told CNBC on Wednesday.

Since the beginning of the year, as of Tuesday's close, the was more than halfway there, with a nearly 2.8 percent advance for February and a 7.9 percent gain for its best January performance since 1987.

"We've never seen two months in a row ever to have every single segment of the U.S. equity market up," Gunzberg said in a "Squawk Box" interview. "I think we could have a good year. But I think it'll look a lot different than it does right now."

"The strength across the board has been driven by the macro picture," said Gunzberg, but argued that going forward whether the U.S. and China reach a trade deal or not, there are going to be companies whose stocks will be winners and losers. "I think we're going to start to see a split in sectors."

It's also worth noting that the gains in January alone have often signaled a strong rest of the year. According to the Stock Trader's Almanac, going back to 1950, the "so goes January, so goes the year" metric has worked 87 percent of the time.

The S&P 500 was still about 5.4 percent from its closing record high on Sept. 20, 2018. The stock market tanked in the final three months of last year, culminating with December's terrible decline of more than 9 percent, the worst final month of the year since 1931. The S&P 500 lost more than 6 percent for all of 2018.