U.S. stocks tick up amid Yellen's testimony

U.S. stocks traded higher in the morning session Wednesday as Wall Street eyed U.S. Federal Reserve Chair Janet Yellen's semi-annual testimony ahead of Thursday's Brexit vote.

By midday, the Dow Jones Industrial Average rose 21.78 points, or 0.12 percent, to 17,851.51. The S&P 500 added 6.14 points, or 0.29 percent, to 2,095.04. The Nasdaq Composite Index went up 21.42 points, or 0.44 percent, to 4,865.18.

Yellen continued her testimony for a second day with a session scheduled Wednesday morning before the House Financial Services Committee.

In her testimony Tuesday before the Senate Banking Committee, Yellen reiterated the U.S. central bank's intention to raise interest rates, taking a cautious approach in view of an uncertain U.S. economy.

She pointed out "considerable uncertainty" about the U.S. economic outlook, which includes slow job gains, weak investment, slow productivity growth, and vulnerabilities in the global economy.

She said that the central bank expected interest rates to remain low for some time, in view of the weak global economy and sluggish productivity growth.

Investors were also counting down the hours to Britain's referendum, which is scheduled to begin Thursday morning.

On the economic front, U.S. existing-home sales sprang ahead in May to their highest pace in almost a decade, according to the National Association of Realtors Wednesday.

Total existing-home sales grew 1.8 percent to a seasonally adjusted annual rate of 5.53 million in May from a downwardly revised 5.43 million in April. Enditem