As goes the European Union, so goes the market. Or at least that's the way it's seemed lately.

While that's meant some glum times over the past few months as eurozone leaders have butted heads over how to address the region's nasty debt situation, it has also meant some breakneck rallies when the heads of state have gotten together and made progress on putting out the fire. Like last night, for instance.

In talks that ran late into the night, eurozone leaders managed to cajole global banks to agree to take a 50% writedown on Greek bonds, an element of the crisis negotiations that had been a sticking point previously. In addition, agreements were reached on leveraging the European Financial Stability Facility -- which would give the fund in the range of $1.4 trillion in financial firepower -- and recapitalizing the region's major banks.

The details still need to be worked out, but global markets have taken this as a cue to switch into rally mode. The market closed well in the black today, with the Dow up 2.9%, while the Nasdaq and the S&P 500 finished up 3.3% and 3.4%, respectively.

Here are some specific areas that you should be watching on the news.

European stocks
Perhaps this deserves a "duh!" but stocks in Europe, and in the eurozone region in particular, are flying particularly high today. Stalwarts like Unilever and Diageo may be shrugging off the news, but more economically sensitive businesses and, even more so, banks, are charging. And rightly so, as stronger footing for the eurozone could mean very good things for the bottom lines of these companies.

Company

Headquarters

Today's Gain

Deutsche Bank Germany 18%
ArcelorMittal (NYSE: MT) Luxembourg 15.3%
National Bank of Greece (NYSE: NBG) Greece 10.9%
Banco Santander (NYSE: STD) Spain 9.3%
Bank of Ireland (NYSE: IRE) Ireland 9%
Telefonica (NYSE: TEF) Spain 6.1%
Siemens Germany 5.6%

Source: Yahoo! Finance.

Financial stocks
Of course, European banks are particularly sensitive to the news about the debt crisis, but there's good reason for banks around the world to view this as good news. Why? For one, many financial companies around the world hold debt from the region. It may not be Greek debt, but the concern was that Italy or even France could be the next targets and paper from those countries is much more widely distributed. Further, as we saw with the 2008/2009 financial crisis, the world financial markets are very interconnected, so major problems in Europe are not something that U.S. banks -- or their shareholders -- can turn a blind eye to.

In other words, there's good reason for investors to be cheering U.S. banks and financial companies as well today.

Company

Today's Gain

Morgan Stanley 16.9%
Jefferies Group 15.9%
Bank of America 9.7%
Citigroup 9.6%
Goldman Sachs 9.5%

Source: Yahoo! Finance.

Economically sensitive industries
A potential stemming of the European debt crisis could mean very good things for the European economy -- or, at least, the avoidance of very bad things. And since we do live in a very interconnected world, that economic goodness could flow from Europe out to the rest of the world. As far as individual companies go, the prime beneficiaries would be those businesses that are particularly sensitive to global economic growth, including industrials, energy companies, and metals and materials players.

Not surprisingly, there are plenty of stocks in these groups that appear to have gained some serious steam from the news in Europe today.

Company

Industry

Today's Gain

Cemex (NYSE: CX) Materials 20.2%
Century Aluminum Materials 19.1%
Manitowoc (NYSE: MTW) Industrials 12%
Patriot Coal (NYSE: PCX) Energy 11.4%
Occidental Petroleum Energy 9.7%

Source: Yahoo! Finance.

Rally on, Wayne!
While the news out of Europe today is important and Mr. Market isn't crazy to be excited about it, it's still just another step in what will be a long process for the struggling countries in the region to work out their balance sheets. As such, investors may want to make sure they're tuned into the stocks they're interested in before trying to chase down the big rally.

To start following along with any of the tickered stocks above, simply click the "+" next to the ticker. What? Don't have a watchlist yet? Well, then, you can easily set one up for free.

The Motley Fool owns shares of Bank of America, Citigroup, Diageo, and Telefonica. Motley Fool newsletter services have recommended buying shares of Jefferies Group, Diageo, and Unilever. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

Fool contributor Matt Koppenheffer owns shares of Cemex, Bank of America, ArcelorMittal, and Siemens, but he has no financial interest in any of the other companies mentioned. You can check out what Matt is keeping an eye on by visiting his CAPS portfolio, or you can follow Matt on Twitter @KoppTheFool or Facebook. The Fool's disclosure policy prefers dividends over a sharp stick in the eye.