Can't this be looked at the other way in that they still retain a significant stake in TSLA? If they thought the company/stock was going to tank, why would they have any stake at all? From what others have said, and i'm no expert on this, funds are only allowed to have a percentage of their assets in any one company. Therefore, any company that has a rapid rise (or slow for that matter) in share price, regardless of company, fundamentals, or these funds analysis of future performance of said company and/or stock, they would have to reduce their stake? If this is the case, the only reason these big funds are reducing their stake is to abide by their own internal rules regarding risk.