The statement by the electric automaker's CEO alludes to "shortsellers", investors who have bet that Tesla shares will fall and who are frequently the subject of Musk's derision.
Einhorn said Tesla has "many parallels" to Lehman, which he said "threatened short sellers, refused to raise capital (it even bought back stock), and management publicly suggested it would go private".
In a separate tweet, Musk took another shot at shortsellers and accused BlackRock Inc of enabling them by saying, "The big funds can & will (sic), as they're suffering a net loss".
Musk came up with a startling announcement that he has considered de-listing the company from the stock exchange. The agency ultimately filed a lawsuit against the billionaire chief executive last week.
Following the SEC settlement, Musk agreed to pay a $20m fine and step aside as Tesla's chairman for three years. Separately, Tesla agreed to pay $20 million to settle claims it failed to adequately police Musk's tweets.
Representatives for the Palo Alto, California-based company didn't respond to requests for comment.More news: The FBI’s Investigation of Kavanaugh Was a Sham
Musk, for his part, has used Twitter to mock Einhorn, saying on August 1 he would "send Einhorn a box of short shorts to comfort him through this hard time".
Tesla and Musk's deal with the SEC would allow Musk to stay on as CEO of Tesla (TSLA) and does not require that he admit wrongdoing.
The SEC settlement still needs court approval.
The sell-off started in morning trading the day after Musk stirred nerves about a settlement of his securities fraud lawsuit by calling the SEC the "Shortseller Enrichment Commission" on Twitter. The judge asked for the letter not to exceed 10 pages and to be double-spaced.
The judge said it was her regular practice to request such letters.
The judge doesn't have to accept the proposed settlement deal.
For her part, Nathan may have limited room to intervene, after a federal appeals court curbed the ability of judges to reject SEC settlements. A higher court eventually sided with the SEC. But that doesn't mean Tesla's board can't order Musk to tone done his Twitter posting in the best interests of the company.