This year’s stock market performance has been impressive by any measure.

The S&P 500 is up almost 20% this year and up 32% so far in the Donald Trump presidency. The Nasdaq is up an amazing 47.5%. (Market nerds will recall that under President Barack Obama’s first 2 1/2 years, the S&P 500 rallied 63% as it recovered from the crash of 2008.)

It was only three years ago then-candidate Trump poo-pooed the stock market as a bubble inflated by low interest rates. Today, he is taking credit for the record highs.

Presidential cheerleading aside, the biggest question in investing today is how long can this keep going. It’s the longest economic expansion in history and there is a lot in the economy that is going right.

As tech stocks soar, Amazon cracks $1 trillion in value, joining neighbor Microsoft

The jobless rate is near a 50-year low. Wages are starting to rise for low wage workers, in part because states have been raising their minimum wages. That is showing up in robust consumer spending numbers. Even all these recent worries about too-low inflation may be overblown. The most recent reading of consumer prices showed a healthy 0.3% monthly gain in the core inflation rate and year-over-year growth of 2.1%.

There’s an old saying on Wall Street: Bulls don’t die of old age.

So what could kill this bull?

  1. The biggest flashing yellow lights are right there in Washington: A grinding Trump tariff regime feels less like a negotiating tactic and more like a permanent condition.
  2. The 2017 tax cuts were a lottery jackpot for American companies, but the benefits are beginning to fade. And the Congressional calendar is a landmine.
  3. The debt ceiling is fast approaching and Congress has to work out a spending deal by this fall.
  4. Another government shutdown, or deep spending cuts, or failing to raise the federal debt limit are all major risks for an economic expansion already long in the tooth.
  5. And then there is the Fed.

Investors may have gotten ahead of themselves hoping for Fed rate cuts. Bubbling above 27,000 in the Dow and 3,000 in the S&P, investors seem to be betting on something more than a single 25-basis point rate cut.

What happens if the Fed doesn’t deliver?

Until then. Enjoy.