The S&P 500 was up 0.4% in midday trading to 2,023.95.

The Dow Jones Industrial Average was up 0.4% to 17,319.87.

The NASDAQ was up 0.5% to 4,752.91.

The yield on a 10-year Treasury bond was up 1.6% to 1.99%.

The price of gold was down 0.1% to $1,230.

FINANCE

Irvine-based Impac Mortgage Holdings Inc. was up 2.4% to $13.44 and a $139 million market cap. Some of the mortgage lender’s preferred shareholders have asked Impac to swap their existing stock for a new class of dividend-paying preferred shares or for common stock.

HEALTHCARE

Irvine-based Biolase Inc. was up 5.7% to $1.49 and an $87 million market cap. The dental laser maker had traded shares by midday at a rate three times higher than its average, and its stock price has risen about 90% over the past three weeks.