"You got to know when to hold 'em, know when to fold 'em," Kenny Rogers sings in his ballad "The Gambler." Gaming stocks investors should give a listen.

Shares of Wynn Resorts, Las Vegas Sands and MGM Resorts fell nearly 8 percent, 6 percent and 3 percent, respectively after Macau gambling revenue results fell short of expectations.

Wynn saw its single worst-day drop since January, when sexual misconduct claims against Steve Wynn were reported, leading to the casino magnate's departure as CEO.

Though shares of the casino crept back to their January highs as recently as May, the stock has been in a near-free fall ever since and traded down to an eight-month low on Monday. And some investors see no signs of letting up.

“When you look at Wynn specifically, you’re looking at an uptrend support line that’s been intact since basically early 2016, and you’re breaking below your 200-day moving average. So from our perspective, it looks like, no, you don’t want to step up and be buying these stocks yet,” Craig Johnson, chief market technician at Piper Jaffray, said Monday on CNBC’s “Trading Nation.”

“I still think you’re going to see more to the downside, and any sort of relief rally we get is just likely that, at this point in time. This is a pretty big uptrend violation,” he said. He's looking at smaller gaming stocks, like casino and racetrack operator Penn National Gaming, which could theoretically be less exposed to international trade tiffs.

Other investors are even more bearish, avoiding the gaming space as valuations remain high, concerns around U.S.-China trade relations linger, and the growth within the Chinese territory of Macau is on shaky ground.

“We would be avoiding the gaming industry altogether, in particular if there are companies that have Chinese exposure overall. So therefore, at this point in time, we would wait and watch the valuation. If it comes down considerably, perhaps we would do that,” said Chad Morganlander, portfolio manager at Washington Crossing Advisors.

Over the past decade, investors have looked to the hot Asian gambling destination to hedge against softer growth in domestic markets.

Macau sales now make up a far larger chunk of U.S. casinos’ overall revenue. Wynn, for example, generated 73 percent of its total sales in the region compared with 52 percent a decade ago.