Gaming stocks have been on a tear since 2009, driven by a nearly tenfold gain for Las Vegas Sands (NYSE:LVS) and a nearly ninefold gain for Melco Crown (NASDAQ:MLCO). But this year, both stocks are down and slower-growing rivals Wynn Resorts (NASDAQ:WYNN) and MGM Resorts (NYSE:MGM) are leading the market. 

The explanation has little to do with operational problems at any of these companies and everything to do with the industry as a whole, and their valuations coming into the year. Growth has slowed in Macau and, with stocks highly valued coming into the year, it has put pressure on gaming stocks. 

Gaming specialist Travis Hoium covers why big gaming stocks are down this year, and what investors should do now.