5 Mid-Cap Stocks With the Highest Gains in April

2. Aehr Test Systems, Inc. (NASDAQ:AEHR)

With a 138.62% gain so far in April, Aehr Test Systems, Inc. (NASDAQ:AEHR) has secured a spot on our list of the mid-cap stocks with the highest gains in April.

That surge in Aehr Test Systems, Inc. (NASDAQ:AEHR)’s share price reflects recent developments that highlight strong demand across hyperscale AI and silicon photonics markets. The company appears to be gaining momentum as a key enabler of AI infrastructure, as it announced a record $41 million follow-on production order from its lead hyperscale AI customer for package-level burn-in (PLB) of custom AI processor ASICs. Those chips are used in data center AI training and inference.

According to the management, the order is the largest in Aehr Test Systems, Inc. (NASDAQ:AEHR)’s history and takes second-half fiscal 2026 bookings beyond the $92 million mark. Management had earlier guided for $60 million to $80 million in second-half fiscal 2026 bookings.

And there is more to it, as the same customer has already placed an initial Sonoma order for its higher-power next-generation AI accelerator ASIC, which is scheduled to enter production later this year. Therefore, the same customer is creating potential for additional demand growth in fiscal 2027. Prior to this win, in late March, Aehr Test Systems, Inc. (NASDAQ:AEHR) secured a major silicon photonics customer as well.

Aehr Test Systems, Inc. (NASDAQ:AEHR) designs, markets, manufactures, and sells test and burn-in equipment used in the semiconductor industry. The company’s products include FOX-XP, FOX-NP, and FOX-CP wafer contact parallel test and burn-in systems, the WaferPak full wafer contactor, the DiePak Carrier, the WaferPak Aligner, the DiePak Autoloader, and test fixtures.