Tesla short-sellers have lost $18 billion this year on the stock's 230% spike (TSLA)

In the same timeframe, traders betting against Tesla have notched $18.08 billion net-of-financing mark-to-market losses, according to data from financial-analytics firm S3 Partners .
A solid part of those losses occured in June and July, according to S3. Tesla short-sellers lost $3.71 billion in mark-to-market losses in June and $4.08 billion in July.
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Traders betting against Tesla have lost billions of dollars this year as the stock surged to multiple fresh highs.

Tesla short-sellers have notched $18.08 billion in net-of-financing mark-to-market losses amid the company's more than 230% rally, according to data released Thursday from S3 Partners, a financial-analytics firm.

The rally was fueled by solid vehicle delivery numbers and a slew of Wall Street analyst upgrades . Next, all eyes will be on the automaker's quarterly profit report July 22.

The last five weeks have been particularly painful for Tesla shorts, accounting for 43% of year-to-date losses, according to Ihor Dusaniwsky, the managing partner of predictive analytics at S3. Tesla short-sellers lost $3.71 billion in mark-to-market losses in June and $4.08 billion in July, S3 data show.

That's led to some short covering, or traders exiting their positions as the stock climbs, sometimes called a short squeeze.

"The reason behind Tesla's short squeeze is obvious and straight forward, large mark-to-market losses are forcing out some short sellers as they hit their loss limit thresholds," Dusaniwsky wrote. Short-sellers have bought-to-cover 1.7 million shares in the last month as Tesla surged 44%, according to S3 data.

In the last week, however, there's been a slight lull in short covering, according to S3. Still, the 98,000 shares covered in the last week were worth a "significant" $133 million, said Dusaniwsky.

Tesla is also on the cusp of a short-selling milestone short interest, or the value of shares shorted, is nearing $20 billion, according to S3. Tesla is likely to be the first company ever to have such a large short interest.

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