It was the week when Elon Musk soared past Bill Gates to become the world's second richest person, as Tesla's value topped $500bn.
On Tech Tent, we ask just why investors think the electric car company is worth so much more than it was a year ago.
At the beginning of 2020, Tesla was valued by the stock market at around $80bn - and even then, sceptics thought that was a high price for a business that was barely profitable.
Throughout the year its shares have soared, and its valuation climbed above $500bn on the news that the business was going to be included in the S&P 500 index of leading companies.
Just to put that into context: Tesla is now worth more than Toyota, Volkswagen, Hyundai, GM and Ford put together.
'You're being too rational!'
