Stocks continued a two-week pullback on Friday, with capital-goods and transportation companies underperforming a weak Dow Jones Industrial Average, which lost 0.4%. Markets moved on sour consumer sentiment data in the U.S., as well as expectations that Moody's may downgrade Spanish debt to junk status.

The Dow Jones Transportation Average has been underperforming all year, and today was no exception, as the index lost nearly 1%. Major gaps between the a weak Transportation Average and a strong Industrial Average have in the past come before broad falls in the DJIA, bringing the two indices into closer alignment.

The transportation index's worst performer was Overseas Shipholding Group (NYSE: OSG), which fell 6.4% to $6.60, well below a 52-week high of $16 and an all-time high of more than $90 per share. Volatile price movements aren't uncommon for the crude oil tanker owner, which now has a market capitalization of around $200 million.

Also broadly down on fears of weak demand in North America and Europe were automakers. Honda Motors (NYSE: HMC) was the laggard of the pack, down 3%. The auto industry did contain a few bright spots, as Tata Motors (NYSE: TTM) and Tesla Motors (Nasdaq: TSLA) both posted impressive gains.

Shares in Tata Motors were up more than 4% Friday, as the Indian automaker's Jaguar Land Rover subsidiary, which contributes a majority of revenue, unveiled a new luxury offering. The Jaguar F-type is planned to enter production in 2013 and compete with Porsche and BMW in the luxury roadster market.

Tesla Motors was up 2.8%, after a week of bad news sent shares plunging. Tesla announced Tuesday that it will offer more shares to pay down debt, a move that will dilute existing shareholders' equity and has already caused a 10% drop. Today, Tesla announced that the new shares will be valued at $28.25, an optimistic price that saw today's shares trading at $29.28.

The day's best industrial performer was electrical equipment manufacturer AZZ (NYSE: AZZ), up more than 9%. The company announced earnings Friday that blew away analyst estimates, growing second-quarter profits by 65%. AZZ also raised its earnings guidance and announced its intent to acquire a Canadian steel galvanizing company.

AZZ has doubly benefitted from low natural gas prices. First, AZZ uses natural gas in its galvanizing process, and cheap natural gas helps the bottom line. More long-term, as utility providers build take advantage of low natural gas prices by building natural gas-powered electrical plants, AZZ will sell them the equipment they need to generate and transmit that electricity.

Of course, putting all that natural gas to work means that prices will eventually turn upwards again. In fact, one Motley Fool analyst believes the natural gas market will turn around by 2014, and he's identified one stock you need to own before then. This report is free, but it's available for only a limited time, so get your copy today.