Smile, Bill Gates! Susan Walsh/AP Photo In July, Bill Gates may or may not have lost his title as the world's richest man. It depends on who you ask.

According to Forbes, Gates has a net worth of almost $82 billion, which puts him in the No. 2 spot behind Mexican telecom magnate Carlos Slim, who's worth $85.4 billion.

According to Bloomberg, Gates is still the world's richest man, worth about $86.5 billion, with Slim at No. 2.

In truth, we don't really know exactly how much Bill Gates is worth, thanks to his uber secretive money manager, Michael Larson, who runs Gates' investment firm Cascade Investment LLC.

Cascade is a private company and doesn't report its earnings. (It doesn't have to.) On top of that, Larson uses all sorts of tricks to hide Gates' involvement in some of Cascade's investments, particularly his real estate holdings, reports the Wall Street Journal.

What we do know is that, from the investments we can track, Gates is at least $6 billion richer right now than he was about six months ago. In March 2014, Forbes said he was worth $76 billion. And that $76 billion was up about $9 billion over his net worth in March, 2013. If we use Bloomberg's number, Gates is up over $10 billion.

A billion here. A billion there. The point is, everyone agrees that Gates is unbelievably wealthy and getting richer all the time.

Interestingly, his wealth is not coming from Microsoft. Back in the day, when Microsoft went public in 1986, Gates owned a 45% stake of Microsoft, or 1 billion shares. Since 1994, he's steadily sold much of that stake: $40 billion worth.

Today, his wealth comes from Cascade. While we'll never know the full extent of its investments, from the public documents Cascade has filed, we do know they include stock in the Canadian National Railway, AutoNation Inc., Berkshire Hathaway, and Republic Services Inc. He also at one time owned significant stakes in Deere & Co, Liberty Global, and Waste Management.

In terms of real estate, he owns stakes in several upscale hotels including the Charles Hotel in Cambridge, Massachusetts, the Ritz-Carlton in San Francisco, the Four Seasons Holding Inc. luxury-hotel chain, and has a 490-acre ranch in Wyoming once owned by William F. "Buffalo Bill" Cody, reports the WSJ.

Surprisingly, his tech investments are relatively sparse. He tends to handle those himself, not through Cascade.

For instance, he founded photo-sharing website Corbis in 1989. He also has a stake in nuclear-reactor developer TerraPower LLC, the meat-substitute maker Beyond Meat (which has also attracted Twitter cofounders Biz Stone and Evan Williams as investors), and ResearchGate, a social network for scientists.

And he still owns Microsoft, just under 300 million shares.

Interestingly, had he kept all of his Microsoft stock, he'd actually be worth more today and be the unquestionable richest man alive. Microsoft's stock has been on the rise since it promoted Satya Nadella to CEO. It's trading above $47.59, with a market cap of nearly $385 billion. So his 45% stake would be worth about $173 billion.

By that way of looking at it, Bill Gates is down by over $80 billion.

He's spending $40 billion on charity through his philanthropic foundation, and his net worth is still growing – and growing fast.