UNITED STATES (REUTERS) - Tesla stock dropped after chief executive Elon Musk abandoned his plan to take the electric carmaker private.

Three weeks ago, Musk shocked Wall Street when he tweeted that he had been considering taking Tesla private. He also said that he had "funding secured" for a buyout at US$420 (S$572) a share.

Tesla stock initially skyrocketed on the news, but it fell nearly 15 per cent since then. Now Tesla is facing an investigation by the US Securities and Exchange Commission, and analysts say it needs new blood in senior management.

One of Tesla's biggest challenges is ramping up production of its mass market, the Model 3, which is critical to its profitability goals.