SOX Index Jumps 4.3% After Adding 4 Stocks in Annual Reconstitution

Q: Which four mystery chip stocks were quietly added to the SOX right before its explosive Monday rally?

The four stocks added to the SOX in the annual reconstitution were **Astera Labs, Credo Technology Group, Macom Technology Solutions, and SanDisk**. Those additions came just before the Philadelphia Semiconductor Index jumped 4.3% on Monday, extending its winning streak to five sessions. The reshuffle replaced four departing names as Nasdaq refreshed the 30-stock benchmark under its annual review process. The additions fit the market’s current semiconductor leadership themes. Astera Labs and Credo are tied to AI and data-center connectivity, Macom has been benefiting from renewed interest in communications-chip exposure, and SanDisk has been one of the sector’s standout memory-related performers. That helps explain why the new entrants were among the names drawing attention as the SOX rallied. In short, the “mystery” additions were **Astera Labs (ALAB), Credo Technology Group (CRDO), Macom Technology Solutions (MTSI), and SanDisk (SNDK)**.

1 articles · Updated · Investor's Business Daily · Sep 21

The Philadelphia semiconductor index climbed 4.3% on Monday after completing its annual reconstitution, extending its regular-session winning streak to five days.
Four newly added constituent stocks helped lead gains after the PHLX Semiconductor Sector Index replaced four other chip names in the annual reshuffle.
The move highlights fresh momentum in semiconductor shares, with the benchmark index advancing even as its membership changed.