The S&P/ASX 200 Index (ASX: XJO) ended May on a positive note, notching a 0.75% gain on the back of a strong late-month rally. Modest as that headline figure sounds, it tells only part of the story — several index constituents delivered returns that left the benchmark far behind.

Megaport (ASX: MP1) — ~70% gain

Megaport was the standout performer of the month, surging roughly 70% to claim the top spot on the ASX 200. The catalyst was a blockbuster contract announcement for its Latitude.sh business: three major GPU, CPU, network, and storage deals across two customers, with a combined total contract value of approximately US$182.9 million (A$254 million). CEO Michael Reid framed the news in broader terms, describing the company as sitting at the forefront of a shift from AI foundation model training toward inference and edge computing — and positioning Megaport's globally distributed, automated infrastructure as essential to that transition.

IperionX (ASX: IPX) — ~42% gain

Titanium alloys producer IperionX climbed around 42% over the month. A likely driver was the successful commissioning of a six-axis powder metallurgy press at its Titanium Manufacturing Campus — a step that expands production capacity and broadens the range of components the company can supply to defense, aerospace, and industrial customers. CEO Anastasios Arima called it an important milestone for the business.

Capstone Copper (ASX: CSC) — ~30% gain

Capstone Copper rose approximately 30% in May, despite releasing no material company news during the period. The gain appears to have been supported by a combination of buoyant copper prices and a UBS upgrade that lifted the broker's price target to $18.00 from $15.00, with a buy rating maintained.

Sims Ltd (ASX: SGM) — ~30% gain

Sims also advanced around 30% over the month. Management's appearance at a major investor conference appeared to boost sentiment, with executives striking a confident tone on the outlook and reaffirming FY2026 guidance. The company continues to target underlying group EBIT of $350–$400 million for the full year — more than double the $174.9 million recorded in FY2025.