Most U.S. universities made money on their financial investments last year, but their returns were tempered by a global economic slowdown fueled by America’s trade war with China, according to an annual survey of school finance chiefs.

The survey, released Thursday, found that college and university endowments returned an average of 5.3 per cent in fiscal year 2019, down from the previous year’s returns of 8.2 per cent and 12.2 per cent the year before that. The returns in 2019 were among the weakest in the past decade, but it’s still seen as a long-term rebound over losses suffered following the 2008 financial crisis.

Harvard University remained the wealthiest school in the U.S., the survey found, with an endowment valued at nearly $40 billion. The University of Texas system and Yale University followed with about $30 billion each, while Princeton University and the Massachusetts Institute of Technology each had more than $26 billion.

More than 100 schools reported endowments topping $1 billion, but the vast majority of schools have far less. Out of all schools surveyed, the median endowment was valued at $144 million, and 3 out of 4 had $500 million or less.

The survey is based on data reported by nearly 800 schools across the U.S. and Canada. It was performed by the National Association of College and University Business Officers, a national group that represents 1,900 colleges and universities, and by TIAA, an investment and banking firm based in New York.

Universities with more than $1 billion saw the greatest returns in 2019, the survey found, with returns averaging just under six per cent. They fared better in large part because they have the money to invest in areas such as venture capital and private equity, which saw some of the strongest returns, the survey found.

Schools that invested larger shares in U.S. stocks also fared well amid a blockbuster year for the nation’s stock market, while those with heavier investments in international stocks drew more modest returns. The groups behind the survey attributed the slump to the U.S.-China trade war, saying it has slowed global trade.

Colleges tend to have different investing strategies based on their wealth, the survey found. The richest schools invest most heavily in a category that includes venture capital funding, hedge funds and private equity, while schools with smaller endowments typically focus on U.S. stocks and bonds.

But schools with $25 million or less, the lowest category in the survey, performed nearly as well as the richest schools in 2019. Their success was credited to their reliance on the U.S. stock market, which had its best returns in six years. The Standard & Poor 500 index, one broad measurement of the U.S. stock market, rose 10.4 per cent in fiscal year 2019.

Still, the groups behind the survey said schools’ shouldn’t strive to match the S&P 500, but should focus on spreading their money over a wide range of investments to safeguard against market swings.

“There are going to be times when the markets are gangbusters and look really good, while these portfolios will not have returns that meet that,” Kevin O’Leary, chief executive officer at the TIAA Endowment and Philanthropic Services, said in a call with reporters. “It’s a balance to create consistent returns to match what we need to spend.”

Most universities in the survey reported that they increased spending from their endowments in 2019, with an average withdrawal of $30 million to support their annual budgets. Overall, about half of their spending went to student financial aid, while the rest was split among academic programs, faculty jobs and other costs.

Some of the nation’s wealthiest schools will soon face a 1.4 per cent tax on their investment earnings as part of a tax overhaul approved by Congress in 2017. It will apply to schools that have at least 500 students and endowments that amount to at least $500,000 per student.

Liz Clark, vice-president of policy and research for the business officers association, said her organization will have a clearer picture of the tax’s impact next year.