Shares of Tesla Motors fell sharply Wednesday after the company, helmed by Elon Musk, made an offer to buy SolarCity for $2.8 billion. Musk is the chairman and top shareholder of the struggling alternative energy provider. Tesla made the offer Monday, in a letter to SolarCity CEO Lyndon Rive, noting that Musk and Antonio Gracias, managing partner of Valor Equity Partners, would recuse themselves from voting on the proposal at the SolarCity board meeting. Both had recused themselves from the Tesla board meeting where the deal was approved.