Western Digital Corp (NASDAQ: WDC) shares are moving lower in Tuesday's after-hours session in sympathy with Seagate Technology Holdings (NASDAQ: STX), which fell after reporting first-quarter results.

Western Digital stock is under selling pressure. Why is WDC stock trading lower?

Seagate Posts Q1 Earnings

Seagate beat analyst estimates on the top and bottom lines in its fiscal first quarter, reporting revenue of $4.23 billion versus estimates of $4.14 billion, and adjusted earnings of $7.68 per share versus estimates of $7.42 per share.

The company guided for fiscal second-quarter revenue of $4.70 to $4.90 billion versus estimates of $4.53 billion and adjusted earnings of $9 to $9.40 per share versus estimates of $8.58 per share.

"Seagate delivered another quarter of record profitability and our highest ever free cash flow in the September quarter, demonstrating the earnings power of our business amid a strengthening demand environment," said Dave Mosley, chair and CEO of Seagate.

Why It Matters For Western Digital

Seagate and Western Digital often trade in tandem because both companies are major players in the data storage market, with performance tied to demand drivers like cloud, AI and enterprise storage spending.

Despite beating estimates, Seagate stock is moving lower after earnings as expectations were likely elevated heading into the print with the stock up significantly over the past year. The weakness has spilled over to Western Digital even though the company already reported its quarterly results.

Western Digital beat estimates on the top and bottom lines last week and issued forward guidance above estimates. Multiple analysts have published updates on the company over the past week with targets ranging from $435 to $668, according to market data.

WDC Shares Move Lower

WDC Price Action: Western Digital shares were down 2.07% in after-hours, trading at $373 at the time of publication on Tuesday, according to market data.