US STOCKS-Wall St rally stamps exclamation point on volatile week
* Crude up as cold wave boosts short-term demand
* Apple rises after Piper Jaffray says buy
* American Express biggest loser on Dow
* Indexes end up: Dow 1.33 pct, S&P 2.03 pct, Nasdaq 2.66 pct (Updates to close)
By Noel Randewich
Jan 22 (Reuters) - Wall Street surged 2 percent on Friday to wrap up its first positive week of 2016 as a cold snap in the United States and Europe sent oil prices sharply higher.
A 4.3-percent jump in the S&P energy sector laid the foundation for the S&P 500's strongest session so far this year.
Crude prices, recently under pressure from a global glut, recovered 9 percent as harsh winter weather boosted demand for heating oil and traders cashed in short positions following a steep drop this month.
After dropping earlier this week to 2014 lows, the S&P 500 has recovered in the past two sessions to end the week 1.4-percent higher. But the index is still down 7 percent in 2016 and remains at levels touched last August when fears of trouble in China's economy rattled global markets. Continuación...