The S&P 500 was up 0.4% in midday trading to 2,789.84.
The Dow Jones Industrial Average rose 0.3% to 25,389.10.
The Nasdaq climbed 0.4% to 7,672.23.
The yield on a 10-year Treasury bond increased 0.9% to 2.96%.
The price of gold was up 0.2% to $1,305.
ShiftPixy Inc. (Nasdaq: PIXY) climbed 8.1% to $2.87 and an $83 million market cap. Shares of the Irvine-based app maker for temporary and shift workers have risen 18% since May 24.
Impac Mortgage Holdings Inc. (NYSE: IMH) in Irvine rose 5.7% to $9.61 and a $201 million market cap. Shares of the mortgage lender have increased 28% since a 52-week low in March.