S&P 500's 4-year bull run: up 117% near records

117% is the headline: the S&P 500 — the index tracking 500 large U.S. companies — is up that much since its 3,577 bear-market close on Oct. 12 four years ago to near records, per Morningstar and Reuters. Big tech and AI stocks drove most of it. The index is up broadly, but only a few giants did the lifting.