Adds dropped letter in former CFO's name in paragraph 9

Feb 25 (Reuters) - Advertising technology firm Trade Desk TTD.O forecast first-quarter revenue below Wall Street estimates on Wednesday amid mounting pressure from larger rivals, sending its shares down over 15% in extended trading.

Unlike "closed" sites such as Google or Meta Platforms' META.O Facebook, Trade Desk is an independent middleman that helps advertisers run campaigns on any website or app they choose.

However, the company faces increased competition from so-called "walled gardens," which integrate content, commerce and user data. Amazon's AMZN.O demand-side platform in particular has become a key competitor, leveraging its vast trove of first-party shopper data to attract advertisers.

Trade Desk is now looking to win broader adoption for newer initiatives such as OpenPath, which lets advertisers buy ads directly from websites. But that's a push analysts believe requires sustained investment and time to scale.

"We executed against a backdrop of macro uncertainty while making some of the most meaningful upgrades in our company’s history," CEO Jeff Green said.

Trade Desk expects a first-quarter revenue of at least $678 million, below analysts' average estimate of $689.2 million, according to data compiled by LSEG.

In the quarter ended December 31, Trade Desk reported a revenue of $846.8 million, compared with estimates of $840.2 million.

Quarterly adjusted profit came in at 59 cents per share, beating estimates of 58 cents per share.

In January, Trade Desk named Chief Accounting Officer Tahnil Davis as interim CFO after Alex Kayyal, who was appointed to the role in August 2025, stepped down.

(Reporting by Anhata Rooprai in Bengaluru; Editing by Jonathan Ananda)

((Anhata.Rooprai@thomsonreuters.com))