Sandisk (SNDK) is set to join the S&P 100 on Monday, but the stock's dramatic pre-inclusion rally has left investors wondering whether the move is purely mechanical or a vote of confidence in the company's pricing power. The Nasdaq-listed memory chip maker closed Friday's session at $1,791.82, up $177.43, or 10.99%, from Thursday's close of $1,614.39. Volume surged to 17.6 million shares, more than double the previous session's 8.48 million, as index funds and benchmark-aware managers positioned ahead of the index change.
The Index Effect
S&P Dow Jones Indices announced Sandisk's promotion on September 4, with the change effective before trading opens on September 21. Friday marked the final opportunity for passive funds to adjust their holdings. The stock opened at $1,624.06, never dipped below $1,616, and closed just $5.18 shy of its intraday high of $1,797. That pattern is consistent with sustained rebalancing demand, though daily data cannot separate forced buying from investors making a fresh bet on NAND flash pricing.
Entry into the S&P 100 broadens the pool of natural buyers for Sandisk shares, but it does nothing to change the company's underlying fundamentals. Once the rebalance trades settle, earnings and cash flow will need to support the new valuation.
Valuation Concerns
Friday's rally added roughly 2.4 turns of annual earnings to the stock's multiple. At the close, Sandisk traded at about 24.3 times its fiscal 2026 GAAP diluted earnings per share of $73.76. That calculation uses the company's full-year result and Friday's closing price, not an analyst forecast. The one-day gain alone was equivalent to nearly 2.4 times those annual earnings per share.
Sandisk's operating results give bulls more than an index-flow story. The company reported fiscal 2026 revenue of $20.25 billion, up 175% year over year, and GAAP net income of $11.43 billion. Fourth-quarter revenue rose 51% sequentially to $8.97 billion, while GAAP gross margin reached an eye-popping 84.6%. Datacenter revenue grew 437% for the year.
The NAND Pricing Puzzle
Yet the composition of that growth is also a warning sign. Sandisk said roughly two-thirds of the fourth quarter's sequential revenue increase came from higher pricing, with only one-third from volume. A valuation built on an 84.6% gross margin is vulnerable if NAND supply catches up, customers resist further price increases, or the product mix becomes less favorable.
Management argues that this cycle can be more durable than past NAND booms. At its August investor day, Sandisk said new business-model agreements with eight customers cover about half of fiscal 2027 bit volume and roughly two-thirds of fiscal 2028 bits. The company's fiscal 2028–2030 framework calls for mid-to-high-teens revenue growth, an approximately 80% non-GAAP gross margin, and an adjusted free-cash-flow margin near 50%. Those targets would support substantial earnings power, but they remain company forecasts and use non-GAAP measures; Friday's closing multiple uses reported GAAP earnings.
What to Watch
Monday's session offers the first separation between the two explanations for Friday's surge. If Sandisk holds most of its gain after the rebalance is implemented, investors are likely assigning weight to the company's pricing framework rather than merely anticipating forced index purchases. A fast reversal on lighter volume would point to a more mechanical move.
The more consequential test comes with the next quarterly report. Sandisk has guided to fiscal first-quarter revenue of $10.3 billion to $10.8 billion and non-GAAP diluted earnings of $44 to $46 per share. Meeting that range would show that the pricing-led step-up continued beyond the June quarter. Missing it would leave investors paying Friday's higher price for margins that may have been closer to a cyclical peak than a new floor.
