One option could be sovereign wealth funds, investment bankers said.
Saudi Arabia's Public Investment Fund has taken a stake of less than 5 percent in Tesla, a source familiar with the matter said on Tuesday. PIF did not respond to a request for comment on whether it would bankroll Musk's take-private deal.
SoftBank Group Corp.'s $93 billion Vision Fund, whose investors include the sovereign wealth funds of Saudi Arabia and Abu Dhabi, is seen as an obvious partner given its appetite for big technology investments, but was not contacted by Musk and is not interested in a deal given its investment in Tesla competitor Cruise, the self-driving car unit of General Motors, according to a source familiar with the matter. SoftBank declined to comment.
China's Tencent Holdings, which took a 5 percent stake in Tesla last year, is another possible partner.
However foreign capital sources would be subject to scrutiny by the Committee on Foreign Investment in the United States, which reviews deals for potential national security risks. Any proposal for funding from Chinese firms could face even tougher checks amid mounting U.S.-China trade tensions.
Many attempts by founders and top executives to take their companies private have never come to fruition. In March, Qualcomm Inc. Chairman Paul Jacobs stepped down from the board to pursue a long-shot take-private bid for the U.S. chip maker, which has a market capitalization of $93 billion. To date, this bid has not materialized.
U.S. department store operator Nordstrom Inc.'s attempt to go private also failed earlier this year, after banks balked at providing the necessary financing to the founding family members seeking to put together the deal.