Between 2021 and 2023 the semiconductor industry faced an acute shortage of FFKM seals, the O-rings and gaskets used in virtually every piece of fab process equipment. The shortage ended only because demand softened in the downcycle; none of its causes were fixed. This two-page briefing sets out the five structural failures behind it, who was hit hardest, the 2026 risk picture, and why qualifying a second source now is the practical mitigation.