One of the world's most widely used browsers began blocking third-party tracking scripts by default this week, a change rolled out silently in a routine update and only confirmed by the company after independent researchers flagged the shift.
The move brings the browser in line with two competitors that adopted similar default blocking over the past two years, leaving one major holdout that continues to rely heavily on tracking-based advertising revenue.
Ad-tech companies reacted swiftly, with several publicly traded measurement firms seeing their stock prices dip on concern that campaign attribution data will become significantly noisier.
Publishers, meanwhile, are being pushed further toward first-party data strategies and server-side tracking, a trend that analysts say has been building for years but is now accelerating faster than most ad budgets can adapt to.