RMBS · CIK 0000917273
What Rambus, Inc. told the SEC could break it.
Rambus's revenue is highly concentrated and overwhelmingly international: two customers alone made up about 23% and 18% of 2025 revenue, its top five reached 66%, and 82% came from international customers, with South Korea its largest geography at $329M. The rest of its register ties back to the China–Taiwan semiconductor zone — it depends on third parties that are its sole manufacturer or sole source of certain materials in regions subject to China–Taiwan tension, and U.S. export controls restrict its ability to send semiconductor products and technology to China without a license. It also notes that its operations and personnel are primarily in the earthquake-prone San Francisco Bay Area.
4 self-disclosed vulnerabilities, pulled from its own filings — each in the company’s words, with the source. This is the risk register almost nobody reads.
In its own words
What could break it.
Geographic concentration
- sole manufacturer / sole-source materials in China-Taiwan zonemedium
Rambus relies on third parties that are its sole manufacturer or sole source of certain production materials, some located in regions subject to China-Taiwan geopolitical tension and export/national-security restrictions.
“may be located in regions subject to geopolitical uncertainty ( e.g. , tensions between China and Taiwan and evolving export/import and national security restrictions).”
- primary operations in SF Bay Area (seismic)low
Rambus's operations, systems and personnel are primarily located in the earthquake-prone San Francisco Bay Area (plus sites in Bulgaria, Canada, France, India, Netherlands, South Korea and Taiwan).
“Our business operations depend on our ability to maintain and protect our facilities, computer systems and personnel, which are primarily located in the San Francisco Bay Area in the United States, Bulgaria, Canada, France, India, the Netherlands, South Korea and Taiwan.”
SEC filing →As of 2026
Customer concentration
- Customer A 23%, Customer B 18% (top 5 = 66%)high
Rambus has high revenue concentration: two anonymized customers were ~23% and ~18% of 2025 revenue and its top five customers were 66%; 82% of revenue came from international customers (South Korea its largest geography at $329M).
“Customer A 23 % 23 % 27 % Customer B 18 % 17 % 18 % Customer C * 12 %”
SEC filing →As of 2026
Regulatory & policy
- US semiconductor export controls to Chinamedium
U.S. export controls restrict sending semiconductor, semiconductor-manufacturing and supercomputing products/technology to China without a license and expand restricted-party lists, constraining Rambus's ability to sell to certain customers.
“the U.S. government has implemented controls affecting the ability to send certain products and technology related to semiconductors, semiconductor manufacturing and supercomputing to China without an export license and added additional entities to restricted party lists in addition to other import/export and national security laws and regulations.”
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