Tesla Motors Inc (NASDAQ:TSLA) CEO Elon Musk, who is known for being candid, has jumped to the defense of his company. Musk was quick to respond to a recent WSJ report that claimed sales for the Model S are down this year.

Tesla Motors Inc Stock Rises As Musk Defends Sales Claim

Musk comments push the stock up

On Tuesday, Musk tweeted “Article in @WSJ re Tesla sales is incorrect,” adding “September was a record high WW and up 65% year-over-year in North America.”

The effect of Musk’s tweet was seen almost immediately, as the shares of the company rocketed 9.5% Tuesday to $242.77 per share, an increase of $21.10.

Are Tesla sales really down?

However, according to a report from Fortune, Musk may be trying to pull the wool over investors eyes, and he may be “guilty of some terminological inexactitude.” It is a bit complicated to identify the exact sales number of Palo Alto-based Company, because unlike other automobile companies who disclose their sales monthly, Tesla reports quarterly numbers.

According to Autodata, its monthly tally of the Tesla United States sales “are based on Tesla’s quarterly estimates and our internal validation process. The numbers are estimates, but (Autodata believes they) are indicative of actual sales results.”

The numbers do indicate a decline in Tesla sales in the United States in the month of September, as well as for the year so far compared to same period last year, says a report from USA Today. The Autodata report also suggests that the company shipped 1,650 cars in September, down 15.4% from the previous year. By Autodata’s count, for the nine months through September, Tesla sold 13,850 vehicles, down 3.2%.

Brian Johnson, in a note to investors on Monday, questioned if the Tesla U.S. sales have “plateaued.”

New lease policy for Model S

On Monday, Tesla announced that it is cutting monthly lease payments by as much as 25% after one of company’s financial partners reduced the cost of lease accounting. This news helped Tesla shares on Monday.

The EV manufacturer said that the demand for Model S is not an issue, but the real concern is the supply. The company is not able to manufacture the required number of Model S vehicles due to its limited capacity at the Fremont factory, which is responsible for fulfilling both domestic and international demand.