Micron fell 13% in one day, and Western Digital, Seagate, and SanDisk fell along with it. But between the hard-drive sellers and the chip sellers, how much does gross margin differ in the latest quarter? Micron's mid-December earnings call fills in the last piece, and the four can be compared side by side: which part of the chain ends up keeping the money?
- Western Digital from 43.5% to 57.8%, Seagate from 39.4% to 57.3%.
- Western Digital 5.1 billion, 60% to 61%, 2.7 points higher.
- SanDisk data center revenue rose 61% quarter-on-quarter, edge only 7%, consumer fell 29%
- Micron's gross margin was 39.8% last fiscal year and 80.7% this fiscal year
- Seagate gave only 4.8 billion and EPS 9.20, without gross margin.
Micron fell 13% in one day, and Western Digital, Seagate, and SanDisk fell along with it. But between the hard-drive sellers and the chip sellers, how much does gross margin differ in the latest quarter? Micron's mid-December earnings call fills in the last piece, and the four can be compared side by side: which part of the chain ends up keeping the money?
美光一天跌 13%，西部数据、希捷、闪迪跟着一起跌，可卖硬盘的和卖颗粒的，最新一季毛利率差多少？美光 12 月中旬的财报电话会补上最后一块，四家可以放在一起比，钱最后留在哪个环节？
The desk answersverifiedWalnut, from public filings
In the same month (July to September), the numbers reported by the hard drive sellers and the chip sellers differ by 27 to 28 points: SanDisk gross margin 85.0%, Western Digital 57.8%, Seagate 57.3%. Micron reports June to August, 86.8%. The money stays on the chip-selling side, and it is not just a little more — the two chip makers' gross profit totals 56.43 billion USD, the two hard drive makers 4.96 billion, an 11x difference.
| Company | Latest quarter | Revenue | Gross profit | Gross margin | Inventory days |
|---|---|---|---|---|---|
| Micron | Jun–Aug | 542.29 yi | 470.47 yi | 86.8% | 131 |
| SanDisk | Jul–Sep | 110.31 yi | 93.78 yi | 85.0% | 166 |
| Western Digital | Jul–Sep | 43.81 yi | 25.34 yi | 57.8% | 88 |
| Seagate | Jul–Sep | 42.33 yi | 24.27 yi | 57.3% | 86 |
Inventory days are calculated by me as ending inventory divided by cost of revenue for the quarter, then multiplied by 91 days; they are not company-disclosed values.
The 28-point gap is not about who bargains better; it is cost structure. SanDisk's cost of revenue this quarter was 1.653 billion USD, versus 1.621 billion a year earlier; revenue rose 378%, while cost barely moved. Western Digital's cost of revenue rose 16% year-on-year, Seagate 13%. What chip makers sell is built fabs and the depreciation sunk into them; selling one more chip costs little extra. For hard drive makers, every additional drive sold requires another set of heads, media, and motors. Converted to gross profit per additional dollar of revenue: SanDisk 99.6 cents, Micron 97.9 cents, Seagate 86.7 cents, Western Digital 83.6 cents.
From a year ago to now: SanDisk gross margin from 29.8% to 85.0%, Micron from 44.7% to 86.8%; Western Digital from 43.5% to 57.8%, Seagate from 39.4% to 57.3%. Of the extra rent from this round of price increases, the chip side took 42 to 55 points, while the hard drive side got only 14 to 18 points.
Micron's segments are even more extreme: core data center 90%, mobile and client 90%, automotive and industrial 84%, cloud storage 83%. Even the lowest is 25 points higher than the two hard drive makers.
Next quarter's guidance diverges for the first time: Micron September to November revenue 61.5 billion, gross margin 85.95%, 0.8 points lower than this quarter; SanDisk October to December 12.2 to 12.6 billion, 84.5% to 85.4%, flat; Western Digital 5.1 billion, 60% to 61%, 2.7 points higher. Seagate gave only 4.8 billion and EPS 9.20, without gross margin. The chip side has peaked; the hard drive side is still climbing.
Micron's mid-December event will update September to November, while the other three need to wait until late January next year for October to December. The four are always one month apart: today Micron lags by one month, after December it leads by one month, and at the end of January it switches back. Only direction can be aligned.
Today all four fell together by 13.1% to 17.3%, packed within 4 points, while gross margins differ by 28 points. On the same day AMD fell 14.5%, Lumentum fell 15.0%, Applied Optoelectronics fell 18.9%, Fabrinet fell 14.7%, and the four semiconductor equipment names fell 7% to 13%. This is not storage's own pricing: the worst faller, SanDisk, is not the lowest gross margin, and the smallest faller, Micron, has the highest gross margin; ranking by gross margin does not produce the decline order. The entire AI hardware chain was repriced on the same day, and the common factor is next year's compute investment.
Where exactly does the money stay? In chips, more precisely in the tier of chips closest to AI servers. SanDisk data center revenue rose 61% quarter-on-quarter, edge only 7%, consumer fell 29%; Micron's core data center segment gross margin is 90%, the highest of its four segments. Hard drive makers earn the same toll, but the absolute amount is an order of magnitude smaller.
The strongest counterargument: these 28 points mainly come from where assets are placed, not from bargaining power. Micron's gross margin was 39.8% last fiscal year and 80.7% this fiscal year; same fabs, same equipment, 41 points more in a year, all from price; it invested 10.774 billion back into equipment in one quarter, 23% of gross profit, while Western Digital invested only 227 million, 9% of gross profit. What price gives, price can take away: once new capacity comes online, depreciation bites chip makers' gross margins first; hard drive makers have lighter assets and costs that move with shipments, so they fall more slowly when prices decline. So "money stays in chips" may only be the position of this part of the cycle, not a long-term structure.
What would count as me being wrong: in mid-December Micron reports September to November with gross margin below 84% (guidance 85.95%), while SanDisk fails to reach 82% for October to December, and both fall together, showing that the chip-side rent is already receding and I was wrong to treat it as sustainable for another quarter. Conversely, if Western Digital comes in below 58% for October to December (guidance 60% to 61%) while the two chip makers hold 84%, then the "hard drives are more durable" half also fails.
Sources: Micron Technology, Inc., a2026q4ex991-pressrelease.htm, 2026-09-30, 0000723125-26-000018; Western Digital Corp., a4ex991-pressreleaseq127.htm, 2026-10-22, 0001628280-26-066882; Seagate Technology Holdings plc, stxq12027pressreleasefinan.htm, 2026-10-28, 0001137789-26-000300; Sandisk Corp., sndkq1-27ex991xpressrelease.htm, 2026-10-29, 0001628280-26-068243. All are EX-99.1 earnings releases from 8-K filings.
同一个月（7 到 9 月）报出来的数，卖硬盘的和卖颗粒的差 27 到 28 个点：闪迪毛利率 85.0%，西部数据 57.8%，希捷 57.3%。美光报的是 6 到 8 月，86.8%。钱留在卖颗粒那一头，不是多一点——两家颗粒厂毛利合计 564.3 亿美元，两家硬盘厂 49.6 亿，差 11 倍。
| 公司 | 最新一季 | 营收 | 毛利 | 毛利率 | 存货天数 |
|---|---|---|---|---|---|
| 美光 | 6–8 月 | 542.29 亿 | 470.47 亿 | 86.8% | 131 |
| 闪迪 | 7–9 月 | 110.31 亿 | 93.78 亿 | 85.0% | 166 |
| 西部数据 | 7–9 月 | 43.81 亿 | 25.34 亿 | 57.8% | 88 |
| 希捷 | 7–9 月 | 42.33 亿 | 24.27 亿 | 57.3% | 86 |
存货天数是我拿期末存货除当季营业成本再乘 91 天算的，不是公司披露值。
差的这 28 个点不是谁更会还价，是成本结构。闪迪这季营业成本 16.53 亿美元，去年同期 16.21 亿，收入涨 378%，成本几乎没动；西部数据营业成本同比涨 16%，希捷涨 13%。颗粒厂卖的是建好的厂房和沉在里面的折旧，多卖一颗不多花多少；硬盘厂每多卖一块盘，就得多买一套磁头、介质、马达。换成每多一块钱收入落到毛利：闪迪 99.6 分、美光 97.9 分、希捷 86.7 分、西部数据 83.6 分。
一年前到现在：闪迪毛利率 29.8% 到 85.0%，美光 44.7% 到 86.8%；西部数据 43.5% 到 57.8%，希捷 39.4% 到 57.3%。这轮涨价多出来的租金，颗粒端拿走四十二到五十五个点，硬盘端只拿到十四到十八个点。
美光分部更极端：核心数据中心 90%、移动与客户端 90%、汽车与工业 84%、云存储 83%。最低那个也比两家硬盘厂高 25 个点。
下一季指引第一次分叉：美光 9 到 11 月营收 615 亿、毛利率 85.95%，比这季低 0.8 点；闪迪 10 到 12 月 122 到 126 亿、84.5% 到 85.4%，横着；西部数据 51 亿、60% 到 61%，高 2.7 点。希捷只给了 48 亿和每股 9.20，没给毛利率。颗粒端到顶，硬盘端还在爬。
12 月中旬美光那场会补的是 9 到 11 月，另外三家 10 到 12 月要等明年 1 月底。四家永远差一个月：今天美光落后一个月，12 月之后领先一个月，1 月底再换回来。能对齐的只有方向。
今天四家一起跌 13.1% 到 17.3%，挤在 4 个点里，毛利率却差 28 个点。同一天 AMD 跌 14.5%、Lumentum 跌 15.0%、应用光电跌 18.9%、Fabrinet 跌 14.7%，半导体设备四家跌 7% 到 13%。这不是存储自己的定价：跌最狠的闪迪不是毛利率最低的，跌最少的美光毛利率最高，按毛利率排不出跌幅。整条 AI 硬件链在同一天被重新定价，共同项是明年的算力投入。
钱到底留在哪个环节？留在颗粒，更准确是留在颗粒里最靠近 AI 服务器的那一档。闪迪数据中心收入环比涨 61%，边缘只涨 7%，消费跌 29%；美光核心数据中心分部毛利率 90%，四个分部里最高。硬盘厂赚的是同一份过路钱，绝对额小一个数量级。
反方最强的一条：这 28 个点主要来自资产放在哪，不来自议价能力。美光上一财年毛利率 39.8%，这一财年 80.7%，同一批厂房同一批设备，一年多出 41 个点，全部来自价格；它一季投 107.74 亿回设备，占毛利 23%，西部数据只投 2.27 亿、占毛利 9%。价格给的，价格也能拿走：新产能一投产，折旧先咬颗粒厂的毛利率；硬盘厂资产轻、成本随出货量走，跌价时掉得慢。所以「钱留在颗粒」可能只是这一段行情的位置，不是长期结构。
什么情况算我看错：12 月中旬美光报 9 到 11 月，毛利率低于 84%（指引 85.95%），同时闪迪 10 到 12 月做不到 82%，两家一起掉，说明颗粒端的租金已经在退，我把它当成还能撑一季就错了。反过来，西部数据 10 到 12 月不到 58%（指引 60% 到 61%）而颗粒两家守住 84%，那「硬盘更耐用」这半边也不成立。
- 01Micron Technology, Inc.，a2026q4ex991-pressrelease.htm，2026-09-30，0000723125-26-000018
- 02Western Digital Corp.，a4ex991-pressreleaseq127.htm，2026-10-22，0001628280-26-066882
- 03Seagate Technology Holdings plc，stxq12027pressreleasefinan.htm，2026-10-28，0001137789-26-000300
- 04Sandisk Corp.，sndkq1-27ex991xpressrelease.htm，2026-10-29，0001628280-26-068243。都是 8-K 的 EX-99.1 业绩稿
## 差距的大部分在资产负债表上
把折旧加回毛利，四家变成美光 91.6%、闪迪 85.4%、西数 60.2%、希捷 59.1%，最宽的一对从 29.5 点变成 32.5 点。这一条先排掉最常见的误读：颗粒端的高毛利不是轻资产占了便宜，它背着全行业最重的厂房，还原之后领先更多。美光期末固定资产 633.10 亿，是本财年收入 1,331.88 亿的 47.5%。
```chart
type: group
title: 折旧还原后，颗粒端的领先没有缩小
unit: %
labels: 美光, 闪迪, 西数, 希捷
values: 86.8, 85.0, 57.8, 57.3
values2: 91.6, 85.4, 60.2, 59.1
legend: 原口径|折旧还原
```
美光的折旧只有年度累计，单季是拿全年 95.03 亿减前九个月 68.62 亿倒出来的 26.41 亿，这个数是算的，不是披露的。
但拿毛利率横比仍然会错，因为资产记在谁的表上不一样。闪迪期末固定资产只有 7.05 亿，是年化收入的 1.6%。
它 10-Q 附注 10 写着，晶圆 substantially all 向铠侠三家合资厂采购，付变动成本加一半固定成本，价格按未来制造成本确定，还要承担合资厂 49.9% 到 50% 的资本开支。翻成大白话：它的成本是成本加成价，厂房不在它表上。所以收入涨了 378%，它的营业成本只涨 2%——这季 16.53 亿，去年同期 16.21 亿。
| 公司 | 固定资产/年化收入 | 年化毛利÷固定资产 |
|---|---|
| 美光 | 47.5% | 3.0 倍 |
| 闪迪 | 1.6% | 53.2 倍 |
| 西数 | 14.8% | 3.9 倍 |
| 希捷 | 12.8% | 4.5 倍 |
年化毛利＝单季毛利×4。同一个 85% 毛利，一个是重资产租金，一个是买卖差价，两者不是一回事。
## 硬盘厂是买家，转嫁要一个季度
这是传导向下走的那一步，也是 28 个点真正的来源。硬盘里要塞 DRAM 和 NAND 做缓存，颗粒涨价对硬盘厂不是收入，是营业成本。希捷 CFO 把这件事说得很直白：
> "The cost of the external component, as you know, compared to a year ago, is now much higher."
> "when we have enough visibility and we have the time to include that cost increase for the external component into our pricing, of course, we do it."
> —— 希捷 CFO Gianluca Romano，2026-10-28 电话会
但同一位 CFO 也补了一句："sometimes it's not so predictable. So we need a little bit of time to adjust." 这轮差价就是这句话：一头卖成本加成的东西，一头买市价的东西再转卖。不是议价能力差，是合同位置差。
指引里方向很清楚：西数 10 到 12 月毛利率 60% 到 61%（non-GAAP，对本季 58.1% 是 +2.4 点），颗粒两家横着——美光 85.95%（低 0.8 点）、闪迪 84.4% 到 85.4%（中值低 0.1 点）。硬盘在追。西数这季每 TB 均价同比涨 28%，希捷把近线产能按长约锁到 2028 年。
但增量还差着。按指引中值算，下一季每多一块钱收入落到毛利：西数 75.3%、美光 79.9%、闪迪 84.0%（西数 non-GAAP，颗粒两家 GAAP，各自口径内对齐）。差距在缩，方向没反。
## 反方：这是周期，且周期自带修复机制
这 28 点不是结构，是周期。美光上一财年毛利率 39.8%，这一财年 80.7%，差出来的四十一点全来自价格；它一季投 107.74 亿买设备，占毛利 22.9%。
更关键的是 HBM：管理层说 2027 自然年的合约价「we have increased that pricing significantly for calendar year '27, which will reset at the beginning of the calendar year to narrow the profitability gap with conventional DRAM」。翻过来就是现在 HBM 比普通 DRAM 便宜，明年年初 reset 补差价。
如果这句兑现，钱会从普通存储流回 HBM，「钱不在最像 AI 那一格」就只在 2026 年内成立。
还有一层更近的反方：美光手机那格毛利率 90%，但位元出货连续两季环比下滑。涨到量退，说明这 90% 里有一部分是需求破坏换来的。硬盘这头相反——西数出货 248EB、环比 +8%，希捷 198EB 创纪录。谁的量在涨，谁的租金更结实。
## 什么算我看错
- 12 月中旬美光报 9 到 11 月，GAAP 毛利率低于 84%（指引 85.95），同时云存储分部没上 85%——HBM 补差价没发生，颗粒端租金在退。
- 反过来，云存储分部上到 87%、核心数据中心从 90% 掉到 85% 以下——钱开始流回 HBM，这条判断错。
- 西数 10 到 12 月低于 58%、希捷 EPS 低于 8.50（指引 9.20）——转嫁没跟上，「硬盘在追」这半边也不成立。
## 收口
四家跌幅挤在几个点内，毛利率差 28 点，跌最深的闪迪还是毛利率第二高的。市场没在给毛利率定价，在给明年的量定价。所以"毛利率高就抗跌"这组数据直接反驳。
钱最后留在"成本钉死、售价放开"的那一头。闪迪是极端样本：成本按未来制造成本定、售价跟着市场走，涨价全额落毛利；美光是半个样本：成本是折旧和利用率，售价是合约加现货；硬盘厂两头都跟着市场走，赚的是从颗粒涨价到自己调价之间那一个季度的时间差。这个时间差正在被长约抹平——希捷的近线已经锁到 2028 年，下一轮颗粒再涨，硬盘厂反应会更快，28 个点会缩。
要盯的不是这季的 28 个点，是 12 月中旬美光那两个分部数。
来源：Micron Technology, Inc.，a2026q4ex991-pressrelease.htm，2026-09-30，0000723125-26-000018；Western Digital Corporation，a4ex991-pressreleaseq127.htm，2026-10-22，0001628280-26-066882；Seagate Technology Holdings plc，stxq12027pressreleasefinan.htm，2026-10-28，0001137789-26-000300；Sandisk Corporation，sndkq1-27ex991xpressrelease.htm，2026-10-29，0001628280-26-068243。以上均为 8-K 的 EX-99.1 业绩稿；三家电话会转写为 Motley Fool 同日版本；闪迪晶圆采购条款出自其 2026-10-30 的 10-Q（0001628280-26-068601）附注 10。