The S&P 500 index on Monday saw a recent bout of trading result in something the index hasn't experienced in more than a year: a pullback of at least 5% since its peak. The S&P 500 index SPX, -1.11% hit 2,716.74 at its low on Monday, representing a decline of 5.4% since its intraday peak at 2,872.87 on Jan. 26, according to FactSet data. The S&P 500 had gone about 406 trading sessions (including Monday) without such a decline, marking the longest such period without a 5% pullback, a fairly regular occurrence in a normal market, in about 20 years. Monday's tumble comes as broader-market selling was intensifying, with the Dow Jones Industrial Average DJIA, -0.87% shedding more than 463 points, or 1.8%, while the Nasdaq Composite Index COMP, -1.07% was off more than 1%. All three benchmarks have been confronting a sharp sell-off amid a rise in yields for Treasurys, notably the 10-year Treasury yield [: TMUBMUSD10Y], which hit 2.88% on Monday, extending its highest level in about four years. Rising yields increase the borrowing costs for U.S. businesses, and these concerns have been intensifying due to the rapidity of the yield climb recently. The equity retreat also follows a mostly stellar start for the year for the Dow, S&P 500 and Nasdaq.