The Nasdaq-100 Had Its Worst Week in 18 Months. History Says the Following Year Has Usually Been Strong.

The Nasdaq-100 dropped 5.5% in the week ending October 16, 2026, its worst weekly performance in 18 months. Semiconductor stock declines and AI spending concerns drove the selloff, putting pressure on QQQ and its mega-cap constituents including NVDA, AAPL, and MSFT.

The historical record offers a split verdict. Since 2010, QQQ has climbed in the following 12 months after 25 of 26 comparable weekly drops, with a median gain of 22%. That is a near-perfect hit rate over a window dominated by post-financial-crisis dip-buying.

Extend the lens back to 1999, though, and the picture weakens. Only 66% of qualifying drops were followed by gains. The gap comes largely from the dot-com bust, when none of the qualifying weeks were followed by a positive year.

Interpretation: the 2010-onward sample captures a long bull regime, while the 1999-onward sample includes the one episode where a tech-led drawdown was the start of a prolonged decline rather than a buying opportunity. The current setup, with semiconductor weakness and AI spending doubts as the catalysts, makes the distinction between those regimes the central question. The source does not establish which regime this resembles.