A friend’s financial adviser was mildly chastising a client some years back over the lack of diversity in his portfolio. Fully 50 percent of the account consisted of just one stock.

"I know. I’m sorry. But it’s Oracle," the client said, noting that the software giant had recently completed a 60-fold run-up in its share price. (Things have slowed; it has merely quintupled in price since 2005.)

Not all of us are shrewd or lucky enough to latch onto such rising stars. But we should be wise enough with our money to see that there are many lesser possibilities, and that we can take advantage of them if we properly diversify our resources among those opportunities.

Nora Everett is bringing this reminder (or in some cases, news flash) to investors near and far. She should know about this topic, as she is president of retirement and income solutions at Principal Financial Group Inc., and is chairwoman of Principal Funds, and sees it as a duty to promote a balanced investment portfolio.

Getting there is relatively easy. Mutual fund ratings firm Morningstar breaks the investment world down into 10 basic baskets of stocks: foreign, high-yield bonds, investment-grade bonds, large growth stocks, large value stocks, mid-cap stocks, REITs (real estate investment trusts), small growth, small value and diversified. These categories don’t rise and fall in tandem with one another. Bonds will have a great year, for instance, while stocks get crushed. Or foreign stocks will perform well when U.S. equities are down.

Or sometimes everybody loses. In such cases the hope is that you lose the least.

In 2018, for instance, investment-grade bonds led the way with a positive return of 0.1 percent in a rather pitiable year for the markets overall. Large growth stocks took top honors in 2017, rising 30 percent in a markedly better investment year, and small value stocks topped the chart in 2016, up 31.7 percent.

Over a 20-year period ending in 2018, Everett’s numbers showed that REITs offered the best annual average return, of 9.65 percent. In fact, they were the best performer more times than any other category. Mid-cap stocks were in second place. The lowest return over that a time came from investment-grade bonds, while foreign stocks came in ninth.

The highest return of all categories, all years, went to high-yield bonds, in 2009, with an impressive 58.7 percent return. And the lowest for the entire period was foreign stocks, which fell 41.8 percent during 2008, a horrible year all around.

Interestingly, a diversified portfolio came in fourth best, performance-wise. It pretty much performed in the middle of the pack during each of the 20 years that were measured.

You can break down asset allocation to subgroups, such as mid-cap growth versus value, or apartment versus hotel REITs. And you obviously can strike out on your own with individual stock and bond selections, as opposed to mutual funds or ETFs. The beauty of diversification is that it works for big funds of individual purchases and that it works for big and small investor alike.

"Asset allocation is relevant whether it’s $1 million or $50,000" in your portfolio, says Everett.