Something historic is happening in semiconductor ETFs.

The iShares PHLX SOX Semiconductor Sector Index Fund (NASDAQ:SOXX) has surged 27.7% thus far in April, a move so large it eclipses every monthly return the fund has posted since BlackRock Inc. launched it in July 2001.

The fund also reclaimed all-time highs last seen in late February and saw 12 positive sessions out of 14 this month.

The record is not just about price. Investors are pouring money into chip ETFs at a pace never seen before.

SOXX has absorbed $2.05 billion in April inflows, more than double its previous monthly record. The VanEck Semiconductor ETF (NASDAQ:SMH) has pulled in $3.4 billion, also an all-time high for the fund.

Combined, the two funds have taken in $5.45 billion this month, as per TradingView fund flows data, a single-month flow record for the category.

Chart: SOXX ETF Eyes Best Monthly Performance Ever

The Ceasefire That Unlocked The Chip Trade

To understand the April surge, rewind to the start of the month. The U.S.-Iran war that began on Feb. 28 had closed the Strait of Hormuz, pushed oil above $100, and frozen ...