The 10-year Treasury yield has climbed sharply in September 2026, reaching an intraday high of 5.23% and closing near 5.17-5.18% as of September 25, its highest levels since 2007. The primary driver is heavy supply from record U.S. fiscal deficits—now projected above 6% of GDP—and elevated corporate bond issuance, particularly by AI hyperscalers competing for capital. Resilient economic growth, sticky inflation readings, and the Federal Reserve’s September rate hike have also lifted real rate expectations and the term premium. Month-to-date, the yield is up more than 40 basis points, with limited remaining catalysts before month-end resolution.