The S&P 500 was off 0.39% to 1,685.03 in afternoon trading Monday.
The Dow Jones industrial average fell 0.28% to 15,516.01, while the Nasdaq slipped 0.37% to 3,599.65.
The yield on a 10-year Treasury bond rose 1.60% to 2.60%.
The price of gold was up 0.43% to $1,327.20 per ounce.
Irvine-based drug maker Allergan Inc. was off about 2% to $90.60 for a market value of $26.85 billion. Michagan drugmaker Perrigo Co. announced Monday its plan to purchase Elan Corp. of Ireland for $8.6 billion. Reports from Bloomberg and Reuters said Allergan had been among among several companies initially interested in Elan. Allergan is expected to report second-quarter results on Wednesday.
Irvine-based heart valve maker Edwards Lifesciences Corp. was down about 2% to $70.28, after closing up about 1% on Friday. The company, which had a recent market value of $7.91 billion, reported better-than-expected second-quarter results after market close on Thursday.
Irvine healthcare software maker Quality Systems Inc. was up about 3% to $21.86 after its stock was upgraded by Sterne Agee from "neutral" to "buy." Quality had a recent market value of $1.3 billion.