Vicor asked the ITC to bar Monolithic Power's AI-server power modules; MPWR reports October 29

The case now sits under the AI rack

On October 9 the US International Trade Commission↗ instituted investigation 337-TA-1526 on a complaint filed September 9 by Vicor▼−13.38% — Vicor, down 13.38 percent today, a power-module maker in Andover, Massachusetts ¹. Twenty entities now face it: the Foxconn▲+1.88% — Foxconn, up 1.88 percent today, Quanta, Luxshare and Delta groups, chipmaker Infineon, manufacturers Flex▼−8.63% — Flex, down 8.63 percent today and Celestica▼−4.52% — Celestica, down 4.52 percent today, and three Monolithic Power companies ¹. For Monolithic, the accused hardware sits in Enterprise Data, the segment behind 38.8% of last quarter's revenue ².

The subject is vertical power delivery: power modules stacked directly beneath high-current processors to shorten the feed into AI accelerators, GPUs and CPUs ³. Vicor is not asking for damages. It asked for a limited exclusion order and cease-and-desist orders, a border remedy that would keep accused products out of the US market ¹.

The accused line is the growth engine

Enterprise Data, Monolithic's AI-server power segment, earned $380.6 million in the June quarter, up 164.3% year over year, 38.8% of record revenue of $980.6 million ². On July 30, ten weeks before the case opened, management lifted the segment's full-year growth floor from 85% to 130% and guided the September quarter to $1.14–1.16 billion; it says its 48V vertical modules ship to multiple customers ². The next report lands around October 29 ².

Vicor has run this play and won it once

In early 2025 the same commission barred imports of infringing power modules and systems from Delta Electronics, Quanta Computer and two Foxconn units; all three groups are respondents again ⁴. Vicor's release on the new case tells server builders and data-center operators sourcing from respondents that they "will need a license" to keep importing. It is a licensing pitch, and the royalty rates it names escalate as the investigation advances toward an exclusion order ⁵.

The two firms were already in court. Monolithic sued Vicor on July 7 in federal court, alleging Vicor used a former engineer working inside chipmaker AMD's▼−6.27% — AMD, down 6.27 percent today Austin lab to obtain confidential data, and says it lost AMD business when Vicor pressed Customs to block its converters ⁶.

Nothing is decided on the merits

Opening the case decides nothing: the Commission has made no decision on the merits, an administrative law judge hears the evidence first, and an import ban would take a full hearing and a final ruling ¹⁷. Orders become final 60 days after issue unless the US Trade Representative disapproves ¹. The Commission must set a target date within 45 days of institution, which lands on November 23 ¹.

Luxshare has a defense Monolithic cannot use

Luxshare told its home exchange on October 11 that it expects no material impact, because its accused data-center power modules are still being tested by customers and have not entered mass production ³⁷. Monolithic cannot say the same: its 48V vertical modules already ship to multiple customers ².

Friday's selloff spared no one. Monolithic closed October 16 at $1,210.86, down 3.1%, and Vicor closed down 12.9% ⁸⁵. Insiders sold $746.3 million of Monolithic stock over the past twelve months and bought none ⁸.

Twelve days to the earnings call

The October 29 call now carries a question written after the guide: does a 130% growth floor survive a border case aimed at the same modules? Watch the November 23 target date, the judge assignment, and whether the company says anything at all.