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Trade Desk logo alongside an S&P 500 removal graphic
Photo: AdTech Radar

Trade Desk Stock Falls 2.4% on S&P 500 Removal

S&P Global2 min read6 sources

Why is Trade Desk stock down today?

Trade Desk (TTD) stock fell 2.4% to $13.92 on Friday as S&P 500 index funds sold an estimated $680 million worth of shares to execute the stock's removal from the index.

Key numbers

TTD close Sept 18$13.92-2.4% on the day
TTD year-to-date-63.3%from ~$38 at start of 2026
Estimated passive sell pressure~$680M~6x average daily dollar volume
TTD market cap$6.6Bdown from $65B peak in Dec 2024
Days inside the S&P 500430Jul 18, 2025 – Sep 21, 2026
Q2 2026 revenue growth+3% YoYdown from +25% a year earlier

What happened

Trade Desk (TTD) stock fell 2.4% to $13.92 on Friday as S&P 500 index funds sold an estimated $680 million worth of shares to execute the stock's removal from the index. The removal, announced September 4, takes effect today with TTD dropping straight to the S&P SmallCap 600 — bypassing the mid-cap tier entirely. Trading on Friday hit roughly 140 million shares, six times the daily average, as passive funds cleared their positions at the closing auction. Trade Desk has now lost 63% of its value this year and 83% since joining the S&P 500 only 430 days ago.

Why it matters

Trade Desk powers the technology behind programmatic advertising — the automated buying and selling of digital ad space running beneath billions of ad slots online every day. When a company exits the S&P 500, every index fund and ETF tracking the benchmark must sell it, creating forced selling unrelated to business quality. For TTD, that pressure adds to an already painful year: the company missed its Q2 2026 targets, guided toward its first-ever quarterly revenue decline, and cut 15% of its workforce.

Who this affects

Marketbearish
High impact
Index funds face ~$680M in forced TTD selling.
Companybearish
High impact
TTD shareholders face continued losses outside the S&P 500.
Competitorsmixed
Low impact
Rivals AppLovin and Magnite may absorb displaced ad budgets.
Industrybearish
Medium impact
Programmatic ad-tech sector faces deepening growth concerns.

Trade Desk vs AppLovin, Magnite, DoubleVerify

Trade DeskTTD$6.6B-2.4%-63.3%~13x+3%
AppLovinAPP$103.1B-4.2%~-53%~20x+53%
MagniteMGNI$3.6B-1.9%—21x+8%
DoubleVerifyDV$2.1Bflat—12x+8%

As of 2026-09-18

How we got here

  1. TTD hits all-time high of $139.51; market cap peaks near $65B.

  2. Trade Desk joins the S&P 500 at an entry price of $80.21 per share.

  3. TTD falls 27% in a day on first guidance miss in 33 quarters.

  4. Q2 2026 earnings miss sends stock down 24% after hours; Q3 guidance implies revenue decline.

  5. S&P announces TTD removal; same day TTD cuts 15% of its workforce.

What to watch

  • TTD opening price Sept 21 as U.S. markets react to official index exit.2026-09-21
  • Q3 2026 earnings — whether TTD posts its first-ever quarterly revenue decline.Q4 2026
  • Google antitrust remedies and whether they lift ad-tech rivals like Magnite.Q4 2026

Educational content only. Not investment advice.

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