The Dow Jones Industrial Average (INDEX: ^DJI) has certainly had its share of ups and downs so far in 2012, with a huge performance in the first quarter almost wiped out by a terrible streak of losing sessions in May. With the average's movements pointing to a lot of uncertainty, it's a good time to come back and look at the fundamentals driving the 30 components of the Dow.

Earnings season isn't quite over yet for the Dow, as the last company, Hewlett-Packard, reports later this week. But among the 29 companies that have reported, the news appears pretty favorable. Let's take a closer look.

Who's winning?
Initially, analysts had low expectations for the first quarter. After a long sequence of weak comparisons leading out of the financial crisis, many investors expected earnings growth to come to a near standstill.

But looking at the actual results, it's clear that lackluster predictions greatly underestimated the prospects of the vast majority of companies in the Dow. According to Yahoo! Finance, 25 Dow stocks beat earnings estimates, while two matched expectations and only two fell short.

One of the biggest winners was the first company to report. Alcoa (NYSE: AA) surprised the entire stock market by posting a profit of $0.10 per share instead of an expected $0.04 EPS loss. In Alcoa's case, it was clearly a case of faring less badly than most investors had feared. It's hard to get too excited about a year-over-year net income decline of nearly 70%, but in the face of much lower aluminum prices, it's still a feat that Alcoa was proud of. Unfortunately, the stock has given back its post-earnings gains, as fears about a slowing global economy have pulled the stock back down to new 52-week lows.

Travelers (NYSE: TRV) was another huge earnings winner, beating estimates by a whopping 32%. After a horrific 2011, the insurance company showed signs that pricing for policy renewals had started to firm up, helping to boost profits. At the same time, Travelers didn't face any huge catastrophic losses during the quarter. The increase in earnings per share is a little bit misleading, as a reduction in the number of shares outstanding masked what was actually a decline in overall net income from the year-ago quarter. Nevertheless, the company's stock gained on the news and has held up pretty well even during the Dow's recent decline.

Finally, Boeing (NYSE: BA) gave investors an earnings surprise of about 30% on the back of a nice combination of positive factors. A big set of new orders helped give investors hope about the company's future prospects, and with production of the long-awaited 787 Dreamliner finally looking like it will ramp up soon, worries about the impact of further delays started to weaken. With cost-cutting measures having borne fruit, Boeing now only needs the global economy not to collapse. Unfortunately, with the stock having dropped about 10% since Boeing's report, it looks like investors fear exactly that.

Who's losing?
ExxonMobil posted a modest miss on earnings, but the big loser appeared to be Bank of America (NYSE: BAC). Posting earnings per share of just $0.03, the company seemed to miss estimates of $0.12 per share by a big margin. But the shortfall came from $4.8 billion in one-time charges reflecting changes in the value of B of A's debt, so many analysts actually credited the company with a big earnings beat.

That wasn't so for CLSA analyst Mike Mayo, though, who downgraded the stock to a sell even as many analysts raised price targets and upgraded B of A. Mayo sees the bank as not living up to its potential, citing weak management as a big factor in failing to get profits back up to their pre-recession levels. Since the report, B of A stock has plunged about 20%, giving back much of its gains from the first quarter.

Time to look ahead
Overall, investors should be happy about the first quarter's earnings season. The problem, though, is that with the second quarter getting off to a rocky start, you can't be sure these gains will be sustainable. For more answers, we'll have to wait until July starts the cycle all over again.

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