SAN FRANCISCO — Bird, a start-up that rents out electric scooters, is being valued at $2.5 billion in a new funding round led by the venture capital firm Sequoia Capital, according to three people with knowledge of the deal.

The funding puts Bird’s valuation slightly above the $2.3 billion that it was pegged at last year. At the time, the $2.3 billion figure represented double the start-up’s previous valuation, as venture capital investors fought to pour money into scooter start-ups.

But that eagerness has deflated over the past year as investors have questioned whether the scooter companies can make money. The scooters have been subject to vandalism and theft, and early models were not very durable and lasted only a few months. Furthermore, after the recent tepid initial public offerings for Uber and Lyft, investors have thought twice about pouring money into unprofitable transportation start-ups with untested business models.

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The total capital that Bird will raise in the new fund-raising has not been finally decided, said the people, who spoke on the condition of anonymity because they were not authorized to speak publicly. Bird said last year it had raised a total of $418 million in funding.