Image source: Las Vegas Sands.

What: Shares of gaming giant Las Vegas Sands Corp. (NYSE:LVS) jumped 19% in July, according to data provided by S&P Global Market Intelligence, as investors bet that the decline in Macau's gaming market will soon come to an end.

So what: Second quarter results released recently showed a 9.3% decline in revenue to $2.65 billion, but hold-adjusted property EBITDA fell just 5.9% to $953.8 million. While still in decline, management said it saw some improvement in Macau, particularly in the mass market, where Las Vegas Sands is a dominant player. 

The company also said it will open The Parisian Macau on September 13, although we don't yet know how many table games the resort will receive. And that table allocation could determine how profitable the property is. 

Now what: It seems that speculation of improvement or decline in Macau is a month to month guessing game. What's clear is that declines are slowing down and the mass market is starting to improve slightly. Long-term, that will be good for gaming companies -- but remember that a number of new resorts will open in the next year, so profits at each property will likely decline over the same timeframe.

The other concern I have with Las Vegas Sands is that it's paying more in a dividend than it's making in net income. That can only continue for so long unless we see vast improvements in Macau. I can see where investors are starting to see signs of hope in Macau, but they should prepare for another up-and-down year ahead. Macau just isn't in a sustainable growth phase yet, and competition is still coming on the horizon, which is something to worry about in gaming.