The U.S. Securities and Exchange Commission has sent subpoenas to Tesla Inc. regarding Chief Executive Elon Musk's plan to take the company private and his statement that funding was "secured," Fox Business Network reported on Wednesday, citing sources.

The electric carmaker's shares fell as much as 4 percent but cut their losses after Goldman Sachs Group Inc. said it was dropping equity coverage of Tesla because it is acting as a financial adviser on a matter related to the automaker.

Investors viewed the Goldman statement as confirming a tweet from Elon Musk on Monday about working with Goldman, even as the reported subpoenas indicated the SEC has opened a formal investigation into a matter.