The bond market just sent one of its loudest warnings in nearly two decades. The 30-year US Treasury yield climbed to 5.12% on Friday — its highest level since June 2007 — while the 10-year benchmark yield rose to 4.57%, breaching the key 4.5% psychological threshold for the first time since May 2025. For equity investors, and small cap investors in particular, this is not background noise. It is a direct threat to valuations, borrowing costs, and earnings growth at the exact segment of the market least equipped to absorb the pressure.