The U.S. stock market on Wednesday set a record for the longest-running upswing in its history, fueled largely by the rise of superstar technology companies and an unprecedented era of cheap money from low interest rates.

The current bull market has been running for almost 9 and a half years, surpassing the dot-com boom in longevity.  The market has created $18 trillion in wealth since the Standard & Poor’s 500 bottomed on March 9, 2009.

A bull market is widely understood to refer to a period when stocks climb without a 20-percent or worse decline.  While the market has wobbled several times since 2009, it has not fallen enough to end the historic run.  Boosted in part by $1.5 trillion of tax cuts passed late last year, the U.S. economy expanded at an annualized rate of 4.1 percent in the second quarter, its strongest performance in nearly four years.

However, analysts see dangers on the horizon.  The world’s most powerful technology companies have played an outsized role in driving the record-setting bull market.  The technology sector, including Apple, Amazon, Google and Microsoft with Facebook neck and neck with Berkshire Hathaway for fifth place, accounts for 26 percent of the U.S. stock market’s value today. The largest sector by far and up from 16 percent before the financial crisis.

Growth has picked up this year after the large tax cuts passed in December, but it is uncertain how long that uptick will last.  Economist cannot fully explain why Main Street has not felt the gains as much as Wall Street.  This sizable disconnect between Wall Street and Main Street is a conundrum that has had far reaching implications for the U.S. economy and politics.

“The U.S. economic expansion is nine years old and could set a postwar record, but about 1 in 3 Americans tell us that they are losing sleep over money,” said Mark Hamrick, senior economic analysts at  He said the rich-poor divide is helping fuel political division that can make the country feel as though it is lurching from one extreme to the next, Hamrick said.

Fifty-two percent of Americans have at least some money invested in the stock market, according to the Federal Reserve.  Among those with money in the market, half have less than $40,000 invested. And, only 8 percent of workers have traditional pensions down from 22 percent in 1989, according to the Boston College Center for Retirement Research.

Many experts say the biggest risk is that inflation picks up quickly after years of dormancy, forcing the Fed to abandon its “slow and steady” pace of interest rate hikes and raise rapidly.  Quick rate hikes can cause firms and families to pull back on borrowing and spending, leading to a slowdown or recession.

Other risks to the market included trade wars and growth slowing overseas.

Federal Reserve officials this month said that a strong economy meant that it would “likely soon be appropriate” to boost their benchmark interest rate for a third time this year.  Also, minutes of their discussions released this week revealed deepening concerns that escalating trade wars could hurt the economy.  The minutes underscore expectation that the central bank is likely to increase its policy rate at its next meeting in September and perhaps another rate hike in December.

A recent poll of more than 100 economists taken August 13-21 showed they expect the U.S. economy to lose momentum. The U.S. economy was forecast to grow 3 percent in the current quarter and 2.7 percent in the next, according to the poll.

The short-term boost to growth from tax cuts was expected to wane, the poll indicated. Economists trimmed their growth projections across most quarters next year leaving the outlook broadly unchanged and vulnerable to the trade conflict with China.

“The trade measures taken by the United States so far and the retaliation by foreign governments will probably slow down the economy marginally,” noted Philip Marey, senior U.S. strategist at Rabobank. “However, that could change in the case of a global trade war in which a range of foreign countries take protectionist measures aimed at the United States,  which is after all the party that is trying to change the status quo.”

Nearly two-thirds of 56 economists who answered an extra question said they have considered the impact of Trump’s expanding trade war in their U.S. growth predictions.

The remaining 20 said the trade dispute has had no influence on their forecasts but underscored the downside risk if trade tensions deepen.  “At this time, with what we know and believe will occur, we acknowledge that risk to the outlook is to the downside with the trade disputes. That said, we have not substantially lowered our U.S. GDP growth outlook. Further deterioration and eventual performance could certainly change our outlook, however,” said Sam Bullard, senior economist at Wells Fargo.

While Trump has said these trade tariffs will benefit the U.S. economy, no economists polled by Reuters shared that view.

All the tariffs imposed and the retaliatory measures until now have been largely confined to Chinese industrial machinery, electronic components and other intermediate goods and has had only a limited impact on the U.S. economy.  However, the next round of tariffs planned for late September are aimed at consumer products and likely to have a negative impact on the overall economy as consumer spending contributes to over two-thirds of U.S. gross domestic product.

While the consensus suggests a slowdown in the world’s largest economy starting next year, only one of over 100 economists polled predicted an outright recession in 2020.

The poll gave a one-in-three chance of a U.S. recession in the next two years, a slight downgrade from a 35 percent probability of that happening in the previous poll. But bond markets are telling a different story. The U.S. yield curve, as measured by the gap between two- and 10- year Treasury notes – is now just 23 basis points, the flattest since just before the last financial crisis. That suggests a yield curve inversion – where the spread goes negative and which has accurately predicted five of the past six recessions – is coming soon.

Despite the threat from trade tensions, the Federal Reserve is still forecast to raise interest rates by 25 basis points in September and once more in December, taking the fed funds rate to 2.25 to 2.50 percent by the end of 2018. For next year, though, economists forecast only two rate increases compared with three suggested by the U.S. central bank’s projections.