Money manager Douglas Gordon is worried about a potentially widespread problem in long-term investors' portfolios.
Gordon, who's instrumental in building Russell Investments' asset allocation strategies, believes many investors haven't rebalanced their portfolios to reflect the historic 2019 stock market rally.
According to Gordon, the market rally's robust gains are tilting investors too far into stocks.
The bottom line: If there's another pullback, it'll leave them wide open to losses that may have been avoidable.
"It's a good time to re-assess where you're at with respect to being diversified in a multi-asset solution," the firm's senior portfolio manager said Friday on CNBC's "Trading Nation. "
Since the Christmas Eve plunge, the has soared 18 percent. Because of the market's sharp rebound, Gordon suspects a 3 to 5 percent sell-off could strike stocks in the coming weeks.
For protection, Gordon recommends taking some profits from the historic rally. Plus, he'd consider going overseas, a strategy he's employing right now as part of a balanced allocation strategy.
"I'd probably right now prefer to take my higher beta exposures maybe in EM [emerging markets]," said Gordon, who's responsible for $48.5 billion of the firm's assets.