Micron Technology is on a tear -- and it was getting another boost on Friday, after one of the flash-memory chip maker's board members signaled that he doesn't expect the rally to end anytime soon.

Shares rose 6.1% to $357.27 in premarket trading, making Micron the S&P 500's biggest winner ahead of the opening bell. Futures tracking the S&P 500 itself were 0.3% higher, as cooling geopolitical tensions helped drive the market higher.

Mark Liu, a former Taiwan Semiconductor Manufacturing executive who now sits on Micron's board of directors, bought 23,200 Micron shares on Tuesday and Wednesday, a filing with the Securities and Exchange Commission late Thursday showed. The shares were worth $7.8 million as of Thursday's close.

The insider purchase could signal to the market that Liu thinks there's still upside ahead for the stock. Micron has soared 218% over the past year thanks to stellar earnings that reflect sky-high demand for flash memory chips.

Other flash memory stocks also were rallying on Friday. Sandisk jumped 5.4%, having closed 5.5% higher the previous session after two analysts hiked their price targets.

Hard-drive maker Western Digital, which spun off Sandisk in February 2025, gained 4.2% on Friday. Peer Seagate Technology added 4.1%.

Those three stocks plus Micron have started 2026 on a tear, with investors betting that memory prices will surge due to sky-high demand for artificial intelligence and server capacity.

Sandisk is up 72% this year, with retail day-traders seemingly piling into shares. Micron, Seagate, and Western Digital have risen 18%, 16%, and 29% respectively.

Trying to catch the rally now could be a risky move, though. Barron's warned earlier this month that investors who load up on shares in Micron and Sandisk could get burned, because of the potential for Chinese rivals to expand aggressively into the memory chip and flash memory space.