Storage — Western Digital Sold the Day Before a 10% Drop, SanDisk Doubled

One book traded this week, and it made one swap. On Thursday AI Build-Out sold its whole Western Digital line, 20.01 shares at 445.29, for 8,910.77 dollars and a gain of 3,280.99. The same day it bought five more SanDisk shares at 1,732.07, 8,661.35 dollars with the fee, which doubles the line to ten shares.

Money went out of the hard-drive maker and into the flash-memory maker, two companies that were one until SanDisk was spun off from Western Digital in February 2025. The swap was close to even in dollars: about 249 dollars more came in from the sale than went out on the purchase.

Friday is why the sale reads well this week. Western Digital fell 10.2 percent to 415.29 after Nikkei reported that Toshiba plans to double its production of hard drives for AI data centers in fiscal 2027; Seagate fell about 11 percent on the same report. That close is 6.7 percent under the sale price. One day is not a verdict on the trade, and several analysts called the drop overdone, so this column will keep the 445.29 line on the record and come back to it.

The SanDisk side has not moved in the book's favour yet. SanDisk closed Friday at 1,719.99, 0.7 percent under the 1,732.07 fill and down 3.3 percent on the week, as memory names gave back some of their run on Friday. The first five shares cost 3,133.13 dollars, about 627 a share, so the line as a whole still carries a gain of roughly 46 percent; the new five shares are the ones bought near the top of that range.

The other news in the log is a split, not a trade. Tokyo Electron split its shares five for one, and the ADR line followed: AI Build-Out now holds 501.36 ADRs instead of 100.27, and Global Tech 50 450 instead of 90. Nothing was bought or sold, and the cost of each line stays the same: 14,748.75 dollars in AI Build-Out and 4,087.87 in Global Tech 50.

One correction to say plainly. The portfolio tracker multiplied the ADR count by five but still marks the ADR at its pre-split price of 164.55 dollars, so it shows both lines about five times too high. Priced from Friday's close in Tokyo, 12,100 yen at 157.9 yen to the dollar and half a share per ADR, an ADR is worth about 38.30 dollars. That makes the AI Build-Out line about 19,200 dollars, a gain of about 30 percent, and the Global Tech 50 line about 17,200 dollars, more than four times what it cost. Until the tracker's quote catches up, these are the numbers this diary uses.

Everything else was dividends, line by line. AI Build-Out reinvested Corning (0.18 shares, now 100.29) on Tuesday, the cybersecurity fund CIBR (0.01, now 200.17) and Broadcom (0.09, now 50.28) on Wednesday, and Nvidia (0.11, now 100.24) on Thursday. Hypergrowth holds the same Corning and Nvidia lines at the same size and reinvested the same two payments. Global Tech 50 added 0.36 STMicroelectronics ADRs on Tuesday, now 250.36; the stock rose 10.3 percent on the week to 57.26.

Global ETFs logged nothing new: the SPMO and QQQM reinvestments in this week's file are dated last Friday and were in last Saturday's entry. That makes eleven weeks in a row without a trade. The derivatives book also logged nothing; its Cloudflare September-2027 250 put sits 28 percent under Friday's close of 349.07.

Where the recent fills stood at Friday's close, said plainly. Nebius closed at 242.81, 14.4 percent above the 212.19 buy-back and 7.6 percent above the 225.56 sale; the two January-2028 250 calls over it are now only 3 percent out of the money. Micron, sold at 976.00, closed at 1,074.89, 10.1 percent above the sale. Qualcomm, sold at 183.74, closed at 184.87, only 0.6 percent above it after a week in which it fell 8.5 percent. Lumentum closed at 1,085.42, 16 percent over its 935.70 fill.

The calls written two weeks ago, against Friday's closes. Corning at 164.19 is 0.5 percent under its 165 strike, so that call is close to being in the money. Rocket Lab at 73.92 is 7.6 percent under 80, and Nubank at 13.43 is 21 percent under 17. The five ASE calls at 40 are 7.45 dollars in the money with the stock at 47.45. In Hypergrowth the short December-2026 250 call on Cloudflare is 99 dollars in the money.

The week those books sat through: the chip fund SOXX rose 2.8 percent and the Nasdaq 100 0.7 percent, while the equal-weight S&P fell 0.7 percent and small caps 0.2 percent. The 30-year Treasury yield rose again, to 5.63 percent on Friday from 5.50 a week earlier. Friday's jobs report showed 29,000 new jobs and unemployment at 4.2 percent. Rubin Build-Out 100 ended the week 5.9 percent higher and Euro-AI 50 2.7 percent higher, while HALO 100 and Agentic Winners 40 each lost 1.1 percent. Prices quoted are Friday's closes; the executed fills sit in the log, line by line.

The four wikifolios that run alongside these books keep their own public ledgers: every transaction in Closelooknet, AI Cycle 2030, ETF Generation and The Compound is visible on wikifolio itself, trade by trade. How the vehicles work, and who the issuer is, lives on the Trade the Look page. Nothing here is a recommendation and none of it is advice: it is the log of what this diary's books actually did between last Friday's close and this one's. The full ledger, newest first, is on the signals page.