Oppenheimer Asset Management's John Stoltzfus is questioning the force of the historic market rally.
Stoltzfus, who is the firm's chief investment strategist, warned clients in a research note this week that "These benchmark moves had even long-term bulls like us wondering if the stock markets are climbing the proverbial 'wall of worry' too fast for this early in a year."
On CNBC's "Trading Nation," he cited tax risks under President-elect Joe Biden as a major piece of his concern.
"We still have certain things that are unknowns about the new administration coming in, particularly if they remove the 2017, 2018 tax reform," Stoltzfus said Wednesday. "It [Wall Street] certainly isn't recognizing those risks from what we can tell."
Stoltzfus credits lower taxes under the Trump administration as a key buffer during the coronavirus pandemic's economic fallout.
"We do believe tax reform helped corporations navigate very troubled waters," he said.
Stoltzfus' hunch is investors and traders are more focused on additional near-term federal virus aid and Covid-19 vaccines versus tax threats right now. He believes the market may be genuinely expecting another round of massive stimulus to offset the loss of tax reform.
Despite his concern, Stoltzfus hasn't changed his 2021 position on stocks. He came into the year with a 4,300 year-end price target on the S&P 500, which reflects a 14.5% increase from 2020's close.
"So as long as the vaccination process is successful, we've got a reopening ahead," Stoltzfus said. "We recommend being exposed to cyclicals and light weight towards defensives at this point."
On Wednesday, the S&P 500 gained a fraction of a percent to close at 3,809.84. The index is up 8.5% over the past three months.