William Blair Investment Management LLC reduced its holdings in Aehr Test Systems by 44.6% during the fourth quarter, according to a May 27 SEC disclosure. The institutional investor sold nearly 400,000 shares, leaving it with a 1.62% stake in the semiconductor company, valued at approximately $10 million at the time of the filing. This news follows a period of high volatility and significant gains for Aehr's stock, which has been buoyed by strong demand in the AI and data center sectors. The disclosure comes just a day before Aehr's CFO is scheduled to hold one-on-one meetings with other institutional investors at the Craig-Hallum Institutional Investor Conference on May 28.