While everyone is fixated on the AI rally driven by mega-cap semiconductor and memory stocks, a far smaller cohort of names has delivered comparable, if not better, performance in June.

According to market data, here are the five best-performing small-cap tech stocks so far in June, screened for market caps between $300 million and $10 billion.

5. Ultra Clean Holdings: Up 31.77%

Ultra Clean Holdings Inc. (NASDAQ:UCTT) makes the subsystems that chip-equipment makers build into their tools: gas-delivery systems, wafer-cleaning modules and chemical-delivery hardware. Its revenue tracks how much gear the industry ships.

On June 8 management met investors at an Oppenheimer broker event. The firm then raised its price target to $115 from $100 and reiterated an Outperform rating, citing a semiconductor-equipment cycle it now sees running stronger and longer than modeled. The stock has roughly tripled year to date.

4. Veeco Instruments: Up 32.38%

Veeco Instruments Inc. (NASDAQ:VECO) builds process equipment used to fabricate advanced logic, memory and packaging, including laser-annealing, ion-beam and deposition systems.

The gain followed a follow-on order for its Nanosecond Annealing System, the NSA500, from a logic customer that had completed an evaluation. Veeco moved with the broader chip-equipment group, which rallied through early June.

3. Arqit Quantum: +33.25%

Arqit Quantum Inc. (NASDAQ:ARQQ) is a UK-based company that sells quantum-safe encryption, cryptography designed to withstand future quantum computers capable of breaking current standards.

On June 1 a U.S. federal court approved a $7 million settlement resolving all outstanding US securities class actions, removing a multi-year legal overhang.

The company had also reported first-half revenue up 829% from a year earlier, off a base of about $623,000.

2. REalloys: +51.14%

REalloys Inc. (NASDAQ:ALOY) is assembling a rare-earth supply chain that bypasses China, running from feedstock to magnet metallization at a facility in Ohio.

The company confirmed inclusion in the Russell 3000 Index effective June 29 and drew a Buy initiation from Needham with a $19 price target.

A letter of intent with Patriot Exploration & Mining added priority access to a large US magnet-metal resource, following an earlier memorandum with Ramaco Resources and a 15-year offtake tied to Greenland's Tanbreez project.

1. Horizon Quantum Holdings: +85.76%

Horizon Quantum Holdings Ltd. (NASDAQ:HQ) is a Singapore-based company that develops hardware-agnostic software meant to make quantum programming function like conventional coding.

Shares jumped after Horizon agreed to install a 256-qubit trapped-ion system from IonQ at its European headquarters in Dublin, a deployment backed by Ireland's National Semiconductor Strategy.

The stock rose 63% in one session and 114% over five days. Needham initiated coverage on June 3 with a Buy rating and a $20 target. Horizon remains in a pre-revenue phase.