Traders and financial professionals work ahead of the opening bell on the floor of the New York Stock Exchange.

The markets have a new fear: FOMO.

In the past few days, as we have reached the heart of earnings season, the markets have again resumed their upward drift. In discussions with traders, there is a new fear on the Street. It is not fear of the government shutdown. It is not fear of a continuation of the tariff war. It is not fear of a China slowdown getting worse.

None of those concerns have disappeared. But there has been a new one added to the top of the list: Fear of missing out — FOMO — on the rally.

"Big money managers cannot get behind of their benchmarks," Tim Anderson, managing director at TJM Investments, told CNBC. "Last year, with the S&P down 6 percent, a lot of big managers were down even more. Now, with the S&P 500 up almost 5 percent this month, you are risking clients saying, 'Hey, you underperform in a down market last year, and now you underperform in an up market?' They are saying, I cannot not buy if the market is going up."

We have had good but not amazing earnings from key financials — Citigroup, Bank of America, J.P. Morgan and even BlackRock. Instead of selling on the news, investors have pushed bank stocks up an average 4 percent this week and 11 percent for the year.

"They finally found a reason to buy," said Peter Tuchman, a NYSE floor trader with QMS Directex. "Those bank stocks were down 20 percent or more last quarter." When earnings came in OK, investors picked up their buying. "They're coming around with shopping lists and fresh cash."

This is largely because expectations are much lower. The market steadily took down earnings expectations for 2019 beginning in the middle of the fourth quarter: