In the middle of last year, Tesla’s losses were piling up, sales weren’t enough to cover expenses and big debt payments loomed. The situation was so bad that one influential Wall Street analyst raised the possibility that Tesla wouldn’t be able to pay its bills and would have to be restructured financially.

Since then, the electric car and solar panel maker’s shares have skyrocketed, rising over 700 per cent this year alone. Monday morning it joined the prestigious S&P 500 index with a market value of over $600 billion. It’s the largest addition in the history of the index.

Tesla’s rise to become the world’s most valuable auto maker and rank among the top 10 biggest US companies is a surprising accomplishment considering that the company lost $1.1 billion in the first half of 2019. The increase is so stunning that even CEO Elon Musk has said the shares are overpriced.

Global sales hit a record of almost 140,000 in the third quarter, debt has been reduced with proceeds from stock offerings, and Musk’s company is building two huge factories. On Monday, the Tesla stock tumbled 4.5 per cent to $663.46 after its inclusion in the S&P 500 index.