High Bandwidth Memory (HBM) is named in Micron (MU) disclosures. It is not presented as a standalone US GAAP revenue line labeled “HBM.” The clearest public demonstration is Micron’s Form 10-K for the fiscal year ended August 28, 2025: the filing defines HBM, places it inside the Cloud Memory Business Unit (CMBU) narrative, and discusses HBM3E and HBM4 shipment or sample milestones without isolating HBM dollars on the income statement.
That boundary is the point of this page. Product commentary can be specific while the financial statements stay aggregated. For the product definition itself, start with the HBM learn page. Delayed Desk quotes for MU sit on the research terminal.
What Micron’s FY2025 10-K actually says about HBM
Open the linked FY2025 Form 10-K first. In that document Micron defines HBM as a 3D stacked DRAM architecture that uses through-silicon via (TSV) connections. The same filing describes CMBU as focused on memory solutions for large hyperscale cloud customers, and HBM for all data center customers. Those sentences locate HBM in the business story. They do not create an HBM-only GAAP caption.
The FY2025 10-K also reports operational milestones: volume production of 8-high 24GB HBM3E began in 2024; in the fourth quarter of 2025, HBM3E 12-high represented the majority of Micron’s HBM shipments; in 2025 Micron delivered samples of HBM4 36GB 12-high to multiple key customers, with HBM4 volume production on schedule for calendar 2026. Markets Desk reading: that is generation, stack, and sample or shipment commentary. It is not HBM revenue, HBM gross margin, or HBM’s share of DRAM sales.
| Disclosure location | What Micron said (FY2025 Form 10-K unless noted) | What that does not prove |
|---|---|---|
| Glossary / business discussion | HBM is a 3D stacked DRAM architecture using TSV connections. | A standalone HBM revenue line on the income statement. |
| Cloud Memory Business Unit (CMBU) | CMBU focuses on hyperscale cloud memory solutions, and HBM for all data center customers. | An HBM-only P&L or a distinct GAAP caption named HBM. |
| MD&A / product commentary | HBM3E 8-high 24GB volume production in 2024; HBM3E 12-high was the majority of HBM shipments in Q4 2025; HBM4 36GB 12-high samples in 2025 with volume production scheduled for calendar 2026. | HBM revenue dollars, HBM gross margin, or HBM share of total DRAM revenue. |
| Later Exhibit 99.1 earnings release | A subsequent earnings press release on EDGAR said HBM4 was in high-volume shipments for a lead customer platform, with qualification samples to multiple end-customers, and HBM4E volume production expected in calendar 2027. | Audited annual statements. An Exhibit 99.1 release is not the audited 10-K. |
A PDF copy of related FY2025 annual-report materials is also on EDGAR at this filing package. Prefer the HTML 10-K above when you want searchable section text.
How to read one Micron filing for HBM
- Open the FY2025 Form 10-K. Start with the linked HTML filing, not a secondary summary page.
- Find the HBM definition and CMBU language. Confirm that HBM is named in the business description before you look for dollars.
- Read the HBM3E / HBM4 shipment and sample paragraphs. Treat stack height and sample language as operational commentary unless Micron also states a product-level revenue breakout.
- Only then check inventory, cost of sales, and gross margin. Those lines are plant-level unless the filing isolates HBM. Do not invent an HBM inventory or HBM margin figure from a total DRAM plant.
- Compare later earnings materials carefully. An unaudited 10-Q or an Exhibit 99.1 release can update HBM commentary. It does not replace the audited annual statements in the 10-K.
For the wider chain outside Micron, see where AI demand shows up in public filings. MU sits in the AI semiconductors theme as a rules-basket memory name, not as a recommendation.
Why inventory and gross margin still matter — and why they mislead
Readers often jump to inventory and gross margin because HBM manufacturing is packaging-heavy. Markets Desk method: use those lines for plant context only. The FY2025 Form 10-K passages cited above do not isolate HBM inventory dollars or an HBM gross margin. A rising inventory balance can mix commodity DRAM, NAND, and advanced products. A mix-driven margin move can come from broader DRAM tightness or other memory products without proving HBM unit shipments.
If a later filing or earnings slide claims an HBM revenue share, verify whether that figure appears in the GAAP statements or only in non-GAAP / presentation materials. This page does not invent such a share.
HBM filing questions
Is HBM a standalone GAAP revenue line at Micron?
No. In the FY2025 Form 10-K, HBM appears in definitions, CMBU narrative, and product commentary, not as its own income-statement caption.
What does CMBU tell you about HBM?
It tells you where Micron places the data-center HBM story organizationally. It does not equal an HBM-only P&L.
Are Form 10-Q statements audited?
No. Quarterly 10-Q statements are unaudited. Audited annual statements are in the Form 10-K.
Primary filings are on SEC EDGAR. How to read a statement is on Investor.gov.