Elon Musk's Companies Have Been Tanking, And He's Lost $1.7 Billion

Tesla and Solar City shares have been getting clobbered.

Both stocks are also down from their highs over the past month - Tesla by 14% and Solar City by 20%. Tesla topped out during the trading day at $291 on Sept. 4 and Solar City hit $76 on Sept. 12.

Elon Musk is CEO of Tesla and Chairman of Solar City, so he's been shedding net worth. How much net worth? He owns over 33 million shares of Tesla and almost 21 million shares of Solar City.

The declines from the peak trading values for those companies have personally cost Musk something on the order of $1.7 billion.

With a total net worth estimated at $10 billion, he's seen 16% of his fortune vanish in September. Of course, he reported being broke back in 2010, so he's no stranger to losing money.

JP Morgan recently joined a chorus of sell-side firms that have sounded a more cautious note on Tesla in recent weeks - a chorus that includes Morgan Stanley, Goldman Sachs, and several other market observers.

Both Tesla and Solar City closed down on Monday: Tesla at $250 per share and Solar City at $61.

On a more upbeat note, Musk is also CEO of private space company SpaceX, which had a successful rocket blast-off over this past weekend and has begun building its own launch facility in Texas.

SpaceX also just nabbed a $2.6-billion contract with NASA to ferry astronauts to the International Space Station.