(Reuters) -Shares of construction firm Fluor Corp ( FLR ) rose 6% in premarket trading on Tuesday after activist investor Starboard Value took a nearly 5% stake, aiming to unlock value from its 40% holding in NuScale Power ( SMR ), two sources familiar with the matter told Reuters.

Starboard founder Jeff Smith is expected to outline the firm's investment thesis at the 13D Monitor Active-Passive Investment Summit in New York later in the day, where he will also discuss plans for TripAdvisor, another recent target.

Shares of NuScale Power ( SMR ) fell 4.7% before the bell.

Analysts at Citigroup said Starboard's stake backs their view that Fluor's shares have room to gain, citing value in the NuScale holding and potential improvement in the company's core operations.

They added Fluor's stake in NuScale still represents more than 60% of its market cap and could sell more of its remaining 111 million shares in the nuclear reactor developer over time.

Fluor's stock is down ~3% so far this year.

Meanwhile, NuScale shares have soared over 145% so far this year, buoyed by rising demand for clean energy solutions to power AI-driven data centers and defense infrastructure.

Both Starboard and Fluor did not immediately respond when contacted by Reuters.

Fluor's core business, which includes infrastructure and energy projects, has come under pressure, with the company posting a 6% drop in second-quarter revenue to $4 billion, missing analyst estimates. Starboard argues the segment is undervalued compared to Fluor's NuScale stake and is pushing for strategic options.

The activist push comes as Fluor is positioned to benefit from infrastructure policies under President Donald Trump, which could boost investment in energy and construction.