Should You Buy Coherent Stock Before It Joins the S&P 500 on March 23?

Photonics and optical connectivity stocks have been in the spotlight lately, riding the boom in AI and data-center spending. Companies building next-generation laser and optical switchgear, essential for hyperscale data centers and 5G networks, are seeing robust demand. For example, Nvidia’s (NVDA) recent $2 billion investment in both Lumentum (LUMN) and Coherent (COHR) signaled confidence in these technologies. Those announcements helped shares of Coherent surge, with the stock now up roughly 31% so far in 2026.

Now, Coherent is poised to join the S&P 500 ($SPX) on March 23, raising a key question: Should investors buy COHR stock ahead of the index inclusion? Let's take a closer look.