Tesla's chief executive Elon Musk held talks with SoftBank CEO Masayoshi Son in April 2017 about the Japanese company investing in Tesla, according to Bloomberg.
The talks touched on taking Tesla private, but failed to progress due to disagreement over ownership, Bloomberg's sources said.
Musk proposed a structure that would have given him disproportionate control over the company through stock with super voting rights, while there are no active talks between the companies now.
Musk announced his plan on his personal Twitter account on Tuesday, and the US Securities and Exchange Commission has asked Tesla about the facts of the matter, why it was disclosed on Twitter rather than in a regulatory filing and whether it believed investor-protection rules had been met, the Wall Street Journal reported on Wednesday.
The agency declined to comment and Tesla did not immediately respond to requests for comment.