Stocks closed out the day slightly down, but posted gains for 2016. This may be a sign of the end of the post-Donald Trump rally, but trading volume was light and we'll have to wait until next year to get a good read on the markets. The Dow gained 13.5% this year, while the S&P 500 rose over 9.5% and the Nasdaq added over 7.5%. Both West Texas Intermediate crude oil and Brent crude, the global benchmark, ended the day lower. But West Texas Intermediate crude oil closed out the year with a 45% gain. Apple (AAPL) - Get Report shares dropped about 1% after the Nikkei Asian Review reported that the technology company will cut its iPhone production by 10%. The financial review said it used supplier data to calculate the drop. And Opko Health (OPK) - Get Report shares tumbled Friday, after the health care company announced that its human growth hormone product clinical programs had "no statistical difference" between its product and the placebo. These upsetting results caused the stock to fall over 20%.