Stock prices were firmer again Wednesday, ending mostly on the highs of the thinly traded and narrow-ranged session that closed early for the holidays. The day's economic data was sparse: Initial jobless claims were reported to have fallen by 10,000 to 214,000 during the week. The Dow Jones industrial average rose 0.6 percent, the S&P 500 gained 0.2 percent to post a record high, and the Nasdaq rose 0.3 percent. US Treasury yields fell, the dollar ended marginally higher, and oil and gold prices were little changed.

Leading gains Wednesday was Dow component Nike, which jumped 4.6 percent partly on news that Apple CEO Tim Cook purchased $2.9 million worth of Nike shares for his own account, and chipmaker Micron Technology, which rose another 3.8 percent, extending its rally in reaction to another surprisingly strong earnings report last week and putting its year-to-date gains at a whopping 240.6 percent.

Market Reflections track market reaction to the trading day's major events. Economic data, policymaker speeches, and company news are featured in this report as well as key indexes and financial instruments.

Understanding why markets respond as they do is fundamental for an investor. Market Reflections help explain how the day's events, news, and data impact the outlook for the economy and for market prices.