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

The U.S. may be close to the peak of its earnings cycle, but earnings still have room to climb — and markets are failing to reflect that potential, according to asset manager NN Investment Partners (NNIP).

Investors seem to have reacted with near indifference to an objectively strong corporate earnings season. Reuters calculated that first quarter earnings were expected to increase 27 percent from the first quarter of 2017.

Of the 465 companies in the S&P 500 index that reported earnings up to May 18, about 80 percent reported earnings above analyst expectations, the wire agency reported. As for revenues, 75.2 percent of companies reported first quarter 2018 revenue above analysts' expectations.

But stock market averages are barely higher than they were at the beginning of the season — as of Tuesday, the S&P 500 was a negligible 0.6 percent higher than it was at the year's start.

Netherlands-based NNIP, in a research note Tuesday, described the market response so far as "lukewarm." Analysts have put this down to earnings expectations being priced-in, a record bull climb in 2017 that couldn't be sustained, and expectations of Federal Reserve monetary policy tightening along with trade war fears.