The S&P; 500 was down about 0.7% to 4,695.09 during midday trading.
The Dow Jones Industrial Average was flat at 36,275.17, while the Nasdaq dipped 1.5% to 14,961.03.
The yield on a 10-year Treasury bond ticked 0.23% higher to 1.727%.
Oil was flat at $82.65 a barrel.
The price of gold decreased 0.6% to $1,816.50 an ounce.
Sonendo Inc. (NYSE: SONX) surged 13% to $8.08 per share and a market cap of $212 million. Shares have now risen 45% since Jan. 10 when the company announced preliminary fourth-quarter revenue ranging from $9.7 million to $9.9 million, topping the average analyst estimate of $9.2 million. The Laguna Hills-based maker of dental technologies went public in October at $12 a share.
Irvine-based medical device maker Masimo Corp. (Nasdaq: MASI) dropped 5.6% to a $241.31 share price and a $13.3 billion market cap. Masimo yesterday reported preliminary 2021 revenue and forecast 2022 revenue will grow 8.9% to 9.3% to $1.35 billion.