A look at ultra-rich families finds they aren't necessarily looking to maximize their investment returns. Most of them concentrate in whole or in part on simply preserving the capital they already possess.

Their main concern is never running out of money.

By the numbers: The UBS Global Family Office Report 2018 looks at where 311 family offices invest their money. Top two takeaways:

These families are rich: The average family net worth is $1.1 billion, while the average amount of assets managed by each family office is $808 million. These families care a lot about liquidity. On average, they have 7% of their assets in cash. That works out to more than $50 million per family, on average.

Even with that large cash allocation, 2017's returns were excellent. Investments rose 15.5% overall, thanks to a great performance from public equities. That was a significant improvement over 2016, when family-office investments rose 7%, and from 2015, when they were basically flat.

There's also a lot of new money here: 67% of the family offices were founded in 2000 or later.

In some ways, though, they're still old-fashioned: Only 9% of the family office CEOs are women.

The asset allocation trends are surprising.

Overall, the families invest only 44% of their wealth in stocks and bonds. There are a lot of private investments, in both companies and properties, which might in part explain why private-equity giant Blackstone sees its assets under management reaching $1 trillion by 2026.

of their wealth in stocks and bonds. There are a lot of private investments, in both companies and properties, which might in part explain why private-equity giant Blackstone sees its assets under management reaching $1 trillion by 2026. But public equities are increasingly popular . Their 28% allocation is up 5 percentage points from 2016.

. Their 28% allocation is up 5 percentage points from 2016. Hedge funds have fallen out of favor, with their 5.7% allocation down 3.2 percentage points from 2016.

"If you look at hedge funds over the last five to eight years, they offer much lower returns than the rest of the market. The purpose of a hedge fund is to limit your downside risk, but you’re not going to get the upside as well."

— The CEO of a family office, quoted in the report