Warsh was confirmed Wednesday in a largely party-line vote.
The S&P 500 slumped 1.7% as soon as trading began, only to churn through another turbulent session.
Investors have waited a long time for San Francisco-based AirBnb to announce its plans for an initial, public offering.
The Dow Jones industrial average crossed the 20,000 mark for the first time Wednesday, the latest milestone in a record-setting drive for the stock market.
Dow Chemical and DuPont are merging to form a company valued at about $130 billion.
Greek Finance Minister Yanis Varoufakis resigned Monday, saying he was told shortly after Greece's decisive referendum result that some other eurozone finance ministers and the country's other creditors would appreciate his not attending the ministers' meetings.
