Stocks dropped for a third straight session on Monday, with tech shares again pacing the retreat. Both the S&P 500 and the Dow Jones Industrial Average lost 0.6% apiece, while the tech-heavy Nasdaq Composite tumbled 1.4%. The averages opened flat, but slipped into the afternoon, settling just above session lows.

The technology sector -- which is the heaviest sector by weight, representing a quarter of the broader market -- was undoubtedly the worst-performing group on Monday, losing 1.8%. More than half of its components shed at least 1.0%, with Twitter (TWTR 31.38, -2.74) losing 8.0%, Netflix (NFLX 334.96, -20.25) dropping 5.7%, and Facebook (FB 171.06, -3.83) tumbling 2.2%.

Monday's tech tumble followed similar declines on Thursday and Friday -- which were set in motion by Facebook's 19% plunge last Thursday following disappointing earnings/guidance -- and points to continued profit taking following a strong run ahead of earnings season; the tech sector added 7.9% from July 3 to July 25.

Elsewhere, Amazon (AMZN 1779.22, -38.05, -2.1%) fell with its FAANG peers, helping to secure a loss for the consumer discretionary sector (-0.8%). The industrial sector (-0.9%) also struggled following an intraday reversal from Caterpillar (CAT 139.75, -2.81), which went from +2.8% to -2.0% despite reporting upbeat earnings and guidance.

On a positive note, the energy sector (+0.8%) advanced, helped by a rise in crude prices; WTI crude climbed 2.1% to $70.10/bbl. The lightly-weighted telecom sector (+2.0%) also had a solid performance, helped by AT&T (T 32.00, +0.92), which jumped 3.0% after being upgraded at Bank of America/Merrill Lynch. Financials (unch) and health care (+0.1%) also outperformed.

Away from equities, U.S. Treasuries finished flat to modestly lower, pushing the back end of the yield curve slightly higher; the yield on the benchmark 10-yr Treasury note climbed two basis points to 2.98%. Meanwhile, the U.S. Dollar Index dropped 0.3% to 94.16, and the CBOE Volatility Index spiked 8.8% to 14.19, a three-week high.

Reviewing Monday's economic data, which was limited to Pending Home Sales for June:

• Pending Home Sales increased 0.9% in June (Briefing.com consensus +0.2%). Today's reading follows an unrevised 0.5% decrease in May.

On Tuesday, investors will receive several economic reports, including the Employment Cost Index for Q2, PCE Prices for June, Personal Income and Personal Spending for June, the S&P Case-Shiller Home Price Index for May, the Chicago PMI for July, and the Conference Board's Consumer Confidence Index for July.

• Nasdaq Composite +10.5% YTD
• Russell 2000 +7.7% YTD
• S&P 500 +4.8% YTD
• Dow Jones Industrial Average +2.4% YTD
• Headines provided by Briefing.com