Fidelity, who remains a stakeholder in the private company and gets insight to internal financials, has cut the valuation of their holding by 75% so far [1]. While twitter might not have been profitable when purchased, it was structured as a growth stock (that is, expected to invest most profit back into the product, in order to continue to multiply revenue) and had yearly revenues of $5B.
1. https://fortune.com/2024/03/30/fidelity-x-stake-73-decline-s...