U.S. stocks have benefited from three "crutches" in recent years, and investors need to focus on whether one of those crutches—earnings—will now support or create drag on equities, analyst Peter Boockvar said Monday.
The Federal Reserve removed one of those crutches last year when it ended its quantitative easing program, but the last support, low rates, will remain in place for some time, the Lindsey Group's chief market analyst said. Earnings are the big near-term variable now.
"Earnings now are looking more flattish year over year, so I think that's the main driver over the next three weeks," Boockvar said on CNBC's "Squawk Box." "That earnings crutch is beginning to change, and that's what investors need to be focused on."
The earnings picture has been mixed thus far. Of the 59 S&P 500 companies that had reported by last week, 75 percent had topped profit expectations, above the 70 percent average for the last four quarters, according to Thomson Reuters. However, only 45 percent of companies beat revenues estimates, compared with 58 percent in the last four quarters.
Investors will get a more complete picture of the first quarter this week as more than a quarter of S&P 500 companies report earnings in the coming days.
Asked whether a weak first quarter will portend a bad year for stock investors, Boockvar said he expects some bounce back in the second quarter, but economic growth may remain unimpressive.
"We're still stuck in this mediocrity of 2 to 2.5-percent-type GDP growth that we can't find a way to get out of, and that's predominantly because productivity is so sluggish," he said.