Warm weather and corporate announcements were some of the catalysts behind the most actively traded stocks on Friday.
Shares of coal-focused energy companies such as Massey Energy , Arch Coal and Peabody Energy moved broadly higher as a heat wave descended on the West and Midwest.
Weather forecasters have predicted a high of 107 degrees in Boise, Idaho, today, which would be six degrees higher than the record of 101 for today's date set in 1985. Meanwhile, Phoenix reached 115 degrees and Baker, Calif., reached 125 degrees yesterday.
"The West Coast is experiencing hot weather and people will use air conditioning more and draw much more electricty off the grid and that could affect how much coal is in demand," said Sara Nunnally, senior analyst at investment newsletter Material Profits. "And since coal supplies 55% of our nation's electricity, that will be a drain."
Nunnally also noted that recent flooding in the Midwest has shut down several railroad supply lines, cutting off supplies of coal and other commodities.
"There has been some severe flooding in the Midwest that shut down tracks by one or two days, and that's why the prices have been rising recently," she added. "We normally see the weather-related disruptions affect natural gas or oil, but not coal, so this is a bit unusual."
Hilton Hotels continued to see a huge pop in trading volume and shares moved higher despite a Bear Stearns downgrade. Analyst Joseph Greff cut his rating on the stock to "peer perform" from "outperform" on Friday, citing a valuation that "largely reflects the current takeover bid" from the Blackstone Group at $47.50 a share, or $26 billion.
"The stock is no longer trading on lodging fundamentals," the analyst added. "Our best idea in lodging is Marriott International given a still relatively reasonable valuation."
In addition to Marriott, Bear Stearns also has "outperform" ratings on Starwood Hotels & Resorts and Sunstone Hotel Investors .
Applied Micro Circuits shares jumped after the company slashed its first-quarter sales outlook, but forecasted higher sales in the second quarter.
Late Thursday, the chipmaker reduced first-quarter sales guidance to $50 million from $59.6 million, citing weakness in the telecom market and disappointing new product sales. However, Applied Micro said second-quarter sales should range from $55 to $60 million, above previous guidance.
Shares of Sun Microsystems and retailers such as Target were also among Friday's most actively traded stocks.
Peter Kang is a markets writer at CNBC.com and can be reached at firstname.lastname@example.org.