Your stock just took a nosedive -- but don't panic. First, let's see whether it had good reason to fall. Sometimes, panic-fueled drops can make excellent buying opportunities. Here's the latest crop of cratered stocks that could provide a possibility for profit:

Stock

CAPS Rating (out of 5)

Friday's Change

ReneSola (NYSE: SOL)

****

(10.5%)

Evergreen Solar (Nasdaq: ESLR)

**

(9.7%)

National Bank of Greece (NYSE: NBG)

****

(8.6%)

On a day when the market opened higher after Fed chairman Bernanke said he was going to continue pouring money into the economy, the market tumbled as banks took a hit on "foreclosure-gate" and within an hour tumbled more than 100 points. While the Dow clawed back to close down just 30 points, Friday's stocks that went big in the other direction are big deals.

The devil's in the details
Last week we asked if investors shorting ReneSola knew something the rest of us didn't. It had one of the biggest percentage increases in shares sold short in the two-week period ending September 30 and is expecting second-half shipments to be as much as 650 megawatts.

Certainly ReneSola's stock has been on a tear, since even after its drop on Friday it is still more than 170% higher than where it was at the start of the year. It isn't alone either. Although not as impressive, LDK Solar (NYSE: LDK) is up 73% year to date and JA Solar (Nasdaq: JASO) is up 60%. While Evergreen Solar has been crawling along the bottom of the solar shop performance table, it had a hot October up until Friday rising 43%.

So profit-taking could be one explanation for the sector's decline last week, but it couldn't have helped that the U.S. trade representative was ratcheting up the rhetoric in the growing -- and potentially disastrous -- trade war between the U.S. and China. It has been a game of tit-for-tat between the Obama administration and China for awhile, and there's growing collateral damage. The Commerce Department slapped China's tubular steel imports with tariffs and China launched an investigation into U.S. carmakers Ford (NYSE: F), GM, and Chrysler sales. When the U.S. raised tariffs on Chinese tires, China retaliated by doubling the tariff on U.S. chicken imports. The House of Representatives recently passed a bill to impose import duties on countries with "undervalued" currencies, generally meaning China's yuan. Monetary policies are quickly affecting trade policy, and the potential for global trade wars grows.

Today it's ReneSola, Evergreen Solar, and other green tech companies feeling the fallout. We know if the Chinese retaliate it's not going to be on U.S. solar shops First Solar (Nasdaq: FSLR) or SunPower, but rather some unrelated industry that relies heavily on exports.

Highly rated CAPS All-Star member ablengata thinks Evergreen Solar is done regardless: "Production costs are just too high. No matter how much improvement the company makes on lowering production costs, it will take this stock a while to heal."

Yet, should ReneSola survive the trade wars, Seansonfire says the Chinese wafer maker has the manufacturing capabilities to grow even further.

ReneSola might not have the technology advantage that other solar producers like FirstSolar or SunPower have, but they have a tremendous growth plan for both Modules and Wafers. Their Modules business is relatively new to the company, reporting their first sales of modules just two quarters ago. ReneSola's impressive manufacturing capacity growth plan will drive their earnings and revenues to double over the next year. They also have shown to have a strong cost advantage on the wafer side which will keep their gross margins up compared to some of their competitors.

The sky's not the limit
It's not trade issues that sank National Bank of Greece last week, but probably the downdraft the financial sector got caught up in as well as looming new international regulations under the so-called Basel III rules.

Greece's sovereign debt woes have spread out to its financial institutions, and National Bank of Greece, as the country's largest, has been hit particularly hard. While the bank has gamely said it doesn't think the country will default on its debt obligations, Greece is already trying to renegotiate the rescue package the EU and IMF arranged for it in May. With riots continuing to break out all over the country, it seems Greece is in a downward spiral.

Yet CAPS member mballiet thinks the recent pledge by China to invest in the country to stave off chaos will help National Bank of Greece recover eventually.

China's investment in Greece will only help. That backing plus the EU will support this investment through the bad times ahead. Hey, you have to have some speculation in your portfolio.

Only you can decide if NBG is right for your portfolio. Add it to your My Watchlist page where all the Foolish news and analysis about this stock is aggregated for you.

Ready for a resurrection
Just because your stock has taken a beating doesn't mean it's going to roll over and die. Markets are known for overreacting. A closer look at what's happened to your stock can give you an edge over other investors who just react to the market's lead.

That's why it pays to start your own research on these stocks on Motley Fool CAPS where you can read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made, all from the stock's CAPS page. Then you can decide for yourself whether it's ready to come back from the dead.

First Solar is a Motley Fool Rule Breakers recommendation. Ford Motor is a Motley Fool Stock Advisor choice. The Fool owns shares of National Bank of Greece SA. Try any of our Foolish newsletter services free for 30 days.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community.

Fool contributor Rich Duprey currently does not own any stocks as you can see here. The Motley Fool has a disclosure policy.