The semiconductor sector just had its worst month in years, and the numbers are not pretty. Global chip stocks declined roughly 13% in July, erasing a staggering amount of wealth accumulated during one of the most euphoric rallies in the industry’s history.

To put that in context: the sector had roughly doubled in value in the first half of the year. July was the bill coming due.

What actually happened

The Philadelphia Semiconductor Index, the benchmark most traders use to track the sector’s health, fell approximately 18% by mid-July. The VanEck Semiconductor ETF dropped 13% over just ten trading sessions in early July.

Memory chip makers took the worst of it. SK Hynix shares fell as much as 15% in a single session on July 13, dragging names like Micron and Seagate down with it.