Stop me if you've heard this one before. The Dow Jones Industrial Average (INDEX: ^DJI) crashes well over 1% on renewed fears about the eurozone as bailouts for Spain look increasingly likely,as does a "grexit." Yeah, I know, just when you think we've baked in all the ugly truth about the eurozone, the markets continue to act surprised at the severity of the issue and send shares starkly lower.

It's been a rollercoaster-like year, with triple-digit pops and drops, and corresponding peaks and troughs in the Volatility index (INDEX: ^DJI), which is up big after another double-digit spike yesterday. After all the turmoil, the Dow is up just 2.6% so far this year, 6% lower than it was in early May, and 3.5% higher than it was in early June.

With soaring Spanish bond yields and Moody's decision to place Germany's debt under review for a potential downgrade, it's easy to want to throw up your hands, stuff your money under the mattress,and forget about investing all together.

But that'd be a horrible mistake.

Domestic markets are actually doing unusually well compared with their international peers, and the major markets are trading at extremely favorable levels. The Dow is trading for a price-to-earnings ratio of only 14.19, less than it was going for at this time last year. What's even better is that the Dow now yields 2.64% instead of 2.4%, as it was at this time last year. So the Dow is cheaper than it was and yields more than it did, and most companies are rocking earnings estimates.

In fact, of the 15 Dow components that have reported so far,only three fell short of analyst estimates, and one of them, McDonald's (NYSE: MCD) would have beat if it weren't for unfavorable currency headwinds. That's why even despite the fearful headlines and the investor angst, I'm excited about Apple (Nasdaq: AAPL) and Caterpillar's (NYSE: CAT) earnings.

Sure, both have the potential for some earnings headwinds. In Apple's case,we may see light iPhone sales as consumers pause for the new phone to be released, and Caterpillar counts Europe as its third largest market, and almost exactly on par with Asia with regard to revenue. However,both companies also have catalysts for outperformance. Apple could hit it out of the park with iPad sales and counter iPhone weakness, and Caterpillar's largest market is still the United States, which is good news as the dollar strengthens.

And you know what? I'd happily own either of them, whether they beat earnings or not. That's because while it's fine to watch headlines quarter to quarter, real investors take a long-view and buy great companies with a buy-and-hold attitude in mind. And when you take a step back, both Caterpillar and Apple still have huge runways ahead of them. Apple is trading at conservative multiples for a company growing this fast, and both Apple and Caterpillar have huge potential in the emerging world.

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