Economists at the Vanguard Group think stocks will continue to grow, but at a lower rate of return in the medium term (of between 4% and 6%), with U.S. stocks trailing international equities. This according to a recent CNBC article.

In a recent report to investors, Vanguard chief economist Joe Davis wrote, “Overall, the risk of correction for equities and other high-beta assets is projected to be considerably higher than for high-quality fixed-income portfolios.”

While the firm sees no signs of market bubbles, Davis argues that rising market returns have in some cases exceeded companies’ improving fundamentals. In the report, he concluded, “For 2018 and beyond, our investment outlook is modest, at best. Elevated valuations, low volatility and secularly low interest rates are unlikely to be allies for robust financial market returns over the next five years.”

In a follow-up interview with CNBC, the article says, Davis clarified that the firm’s outlook is focused on the next five years. “We’re never going to be able to accurately forecast what equity markets do on a one-year horizon,” he said, “But the odds are increasing that returns over the next two to three years are lower than they have been historically.”

As far as the broader economy, Vanguard sees that modest global growth and “tepid” inflation will be reflected in continued low volatility. Investors, according to Vanguard, should pay more attention to low unemployment rates than to GDP growth for indications of “high spending for capital expenditures or wage pressures.” Further wage increases, says Vanguard, could result in “unexpected shocks” to the economy.