(Bloomberg) -- While US equities churn near all-time highs, one of the most closely watched indexes is mired in its longest losing streak since Jimmy Carter was president.

The Dow Jones Industrial Average ended the day 0.6% lower for its ninth straight decline, which marks the blue-chip gauge’s longest losing streak since 1978. The 30-stock index is down 3.5% over that stretch.

The Dow industrials has been dragged down primarily by UnitedHealth Group Inc., the medical insurer whose shares have been in a tailspin since the Dec. 4 shooting of executive Brian Thompson outside an investor conference in New York. The stock is down nearly 21% since then, accounting for 57% of the blue-chip index’s drop.

While UnitedHealth has been the biggest anchor, more than two-thirds of Dow Jones members have fallen over the period. Nvidia Corp., the second-largest company in the world, is down 10% in that time. Sherwin-Williams Co and insurance provider Travelers Cos. are both down roughly 7%.

Meanwhile, Boeing Co. has jumped 9.3% in the nine days and is the top-performing stock in the index even as it continues to be the biggest laggard year to date. Other notable gainers include mega-cap tech names Amazon.com Inc., Apple Inc. and Microsoft Corp. — though they provide less of a boost to stock price-weighted Dow than they do for cap-weighted S&P 500. The Magnificent 7 tech cohort has climbed around 8% in that period, buoying the broader indexes.

--With assistance from Matt Turner.

(Updates with closing share moves)