Read full story for latest details. : Elon Musk said Monday on Twitter that he is working with Goldman (GS) and the investment firm Silver Lake on his proposal to take Tesla private. Goldman also announced Wednesday that it is removing its rating and price target on Tesla (TSLA) stock. That's a step banks like Goldman typically take when they provide advice to a company its analysts also cover. Musk stunned Wall Street last week when he said on Twitter that he intended to take Tesla private at $420 per share, and added that funding was secured.