Throughout the turbulence of his first months in office, President Trump has been able to point to one bastion of support: the stock market. Earlier this month he tweeted the “great economic news” he thinks the mainstream media has been ignoring: The Dow Jones industrial average was up 16 percent and the Nasdaq up 19.5 percent since his election. Commerce Secretary Wilbur Ross maintained that the Trump administration had bestowed $4 trillion in gains on investors.

Investors have seemingly been oblivious to claims of Russian interference in the election, the firing of a director of the Federal Bureau of Investigation, and the appointment of a special prosecutor. As the second quarter ends this week, 2017 has so far been a banner year, with major indexes hitting records.

But as the bull market rolls on, some see storm clouds on the horizon. “Valuations are high and it’s one of the longest and largest bull markets in history,” said James Stack, president of InvesTech Research. “Bull markets don’t last forever. So the question is, when will the music stop?”

Investors “are on a knife’s edge,” said Michael J. Kelly, global head of asset allocation for PineBridge Investments. With many still scarred by the financial crisis, “they see a potential disaster around every corner.”