Elon Musk is no stranger to big expensive bets, but his $US43 billion takeover offer for Twitter raises an important question. Can he afford it?

Musk made his move not long after Twitter announced it had failed to reach an agreement with him about joining its board.

Musk has only just disclosed that he had purchased more than 9 percent of Twitter.

But his willingness to make the deal is now being met with questions about his ability to actually complete it — not just Twitter’s willingness to accept it.

Can he afford it?

Right now, according to Bloomberg, Musk has about $3 billion in readily accessible cash.

So he would have to find the money to complete the deal some other way.

That could include selling more shares in Tesla, or raising the cash through debt.

Musk owns about 173 million Tesla shares. But securities filings show that 88 million of them are being used to back personal loans.

In a securities filing, Musk says the proposal is his “best and final offer” while reiterating his disagreement with Twitter’s leadership over the company’s direction.

At least one major shareholder has already announced his opposition.