The party might be over soon for the 9-year-long bull market, J.P. Morgan strategist David Kelly told CNBC.
"This economy will slow [in the] second half of 2019, 2020," Kelly, who is chief global strategist at J.P. Morgan Asset Management, said Wednesday on "Power Lunch."
After President Donald Trump signed into law the Tax Cuts and Jobs Act of 2017 last December — slashing the corporate tax rate nearly in half — rising economic activity seemed to have no end in sight.
"Fiscal policy is sort of at its maximum accelerated right now," Kelly said.
In fact, unemployment rates have fallen to an 18-year historic low of 3.8 percent, and U.S. nonfarm payrolls added 223,000 — far more than economists anticipated — during the last jobs report in May.
Even escalating trade tensions and higher oil prices haven't stopped the Dow Jones industrial average, a major indicator of economic activity, from setting record highs, now holding steady above the 25,000 mark.
But Kelly said these effects are "probably temporary."
"We got all this sugar rush of fiscal stimulus right now," he said. "But it's a sugar rush."
While Kelly said present earnings are "wonderful," he also said his firm does not expect continued earnings growth.
Investors, he said, "appreciate just how much money companies are making this year. I just think we really need to recognize that the earnings are being front-loaded here."
He pointed out that equity investing is "all about future earnings growth."
"Right now the U.S. is leading the world," he said.
But, he said, "When the rest of the world catches up, I expect international stocks to outperform U.S. stocks over the next few years."
On Wednesday, the U.S. Federal Reserve announced a rate hike of its benchmark short-term interest rate a quarter percentage point to a new range of 1.75 percent to 2 percent. The bank also indicated that further rate hikes will likely be ahead for a total of four rate hikes this year, compared with three rate hikes in the prior 12-month period.
The central bank's rate hikes have long been viewed as a way for the Fed to slow economic growth before the economy overheats.
Kelly said the rate hikes are a positive sign and that it is important for the Fed to get the economy "back to neutral pretty fast" so it doesn't overheat.
"But we don't want to be too aggressive here because we know monetary policy works with a lag," he said.
Inflation is another key ingredient in recessions. While fewer people out of work is a good thing, it also means companies have higher payroll expenses. That often leads to companies raising prices. More rate hikes could lead to inflation.
During Wednesday's Fed announcement, the committee indicated that core inflation should reach the Fed's 2 percent target by the end of the year.
Kovacevich pointed out that Fed Chairman Jerome Powell "admits that there's been very little increase in wages."
Wages have increased — up 2.6 percent in April year over year. But that number is still lower than the previous 12-month period where wage growth increased 2.7 percent.
"We're now in a situation where there's been a huge reduction in discretionary income with the consumer," he said.
Less consumer spending can also lead to a recession.
Instead of talking about 2-percent inflation, Kovacevich said, "we should be talking about stable inflation."
"I don't think they should be trying to inflate the economy," he added.
Still, Kovacevich said "times are reasonably good."
"If we continue to reduce regulations and keep taxes low and keep inflation controlled, there is no reason why this expansion can't continue," he said.
The Fed anticipates that the economy will also continue on its current accelerated trajectory: The Fed anticipates economic growth to hit 2.8 percent for the full year and unemployment to fall to 3.6 percent.
A recession may not be imminent, but Kelly said there are some things investors can do to protect their portfolios in the meantime.
While he said it was "fashionable" to pull back from international stocks at present, he also said market watchers should consider international stocks as a long-term investment.
"If I was going to be very tactical, I would be overweight U.S.," he said. "I would certainly be level weight U.S. relative to international right now."
"But long-term, I'd want to have a little bit more of an overweight toward international, as the rest of the world will grow faster in the long run than we do, both in terms of economic growth and earnings," Kelly said.