AI Hardware Trade Splits: Western Digital Rallies as Coherent Faces Post-Earnings Reckoning

The AI infrastructure trade is no longer moving as a single block. Western Digital rallied as the market reassessed the storage cycle, where constrained supply and surging data-center capacity requirements are translating into pricing leverage that flows quickly to the bottom line. At the other end of the chain, Coherent's shares gave back ground after results, with analysts arguing the pullback looks appropriate given how much forward optimism was already embedded in the optical and photonics complex. The divergence matters for positioning: components with genuine supply tightness and short lead-time pricing power are being rewarded, while names whose multiples anticipate flawless multi-year execution face asymmetric downside on any guidance wobble. Elsewhere in the growth cohort, CuriosityStream's 40% surge drew an upgrade on fundamentals rather than momentum, and Boost Run reported second-quarter revenue of $31.1 million, up 270% year-over-year. The message from the tape is that investors are increasingly willing to pay for demonstrated unit economics — and increasingly unwilling to pay for narrative alone.