SpaceX boss Elon Musk has recently teased that something massive is in store for his electric car company Tesla. This comes after the company is being investigated for a possible securities law breach for failing to disclose a fatal car crash to investors.

Earlier this week, the SpaceX boss took to Twitter to share his thoughts on his business. He teased his followers that he and his team are working on something big for Tesla, which will be revealed soon.

"Working on Top Secret Tesla Masterplan [sic], Part 2," Elon Musk tweeted. "Hoping to publish later this week."

According to Inc., the tweet may be the SpaceX boss' response to criticisms that he has faced. It was noted that, late last month, Tesla offered to buy SolarCity, the solar-energy company that Musk co-founded which is being led by his cousin Lyndon Rive.

The announcement resulted to a 10 percent drop in Tesla's stock as analysts deemed the potential deal as a conflict of interest. SolarCity is deemed as unprofitable since its stock dropped by 15 percent in Q1 2016.

It was previously reported that the SEC is investigating the company on whether Tesla Motors Inc. has breached securities law. It has allegedly failed to disclose to investors a fatal crash in May which involved the autopilot feature of their electric car.

The accident on May 7 killed the driver Joshua Brown, 40, after his Tesla car crashed with an 18-wheel semi-truck on a Florida highway. The company alerted the National Highway Traffic Safety Administration to the crash.

Speaking to Fortune via email, the SpaceX boss and Tesla co-founder deemed that the crash "is not material to the value of Tesla." The Part 2 of this "Top Secret Tesla Master plan" could be about their electric cars' autopilot feature, Inc. added.

In 2006, Elon Musk wrote about Tesla's master plan of initially building a sports car and, afterwards, building more affordable versions from profits gained. The affordable version, a Tesla Model 3 which is priced at $35,000, will be available late next year.