Well... that was awkward. Just when you thought it was fine to go back in the water and all the European debt crisis worries of 2012 were behind us, a Portuguese bank made a bigger "oops" than the Portuguese national soccer team at the World Cup. The Dow (DJINDICES:^DJI) dropped 71 points Thursday on fresh fears out of Europe.

1. Portuguese bank's (minor) default freaks global markets
We need some Espirito Santo! to help with the sudden bank panic that hit Europe on Thursday. News hit the wires that the parent company of Portugal's second biggest bank, Banco Espirito Santo, had to delay interest payments on some of its debts recently because it's in such rough financial shape.
How is this such a sudden surprise? Because the bank was hiding weaknesses with accounting acrobatics. The Portuguese Central Bank found out, and the news hit European investors like a ton of bricks, reminding them of the European debt crisis that still stinks in our memories. Portugal was, after all, one of the PIIGS, the acronym standing for the five debt-crippled countries that ignited the crisis.

The percentage of the day is -17%. That was the drop in Banco Espirito Santo's share price Thursday before regulators cited the Mercy Rule, and suspended trading of the stock for the day. Stock indexes from Great Britain to Germany to Russia tumbled like lightly brushed Christian Ronaldos to the ground. Even the U.S. got hit.
The takeaway is that investors are scared that this might become bigger. One obscure Portuguese Bank doesn't sound scary to many, but in Europe, history has shown that bank sicknesses can spread like wildfire. Investors rushed their money out of stocks to "safe havens" like U.S. and German government bonds.

2. Potbelly plummets as sales projected to drop
If you're trying to bulk up for beach season, you probably haven't been dining at Potbelly (NASDAQ:PBPB). Shares of the struggling sandwich chain plummeted 25% Thursday after the CEO warned investors that the company is estimating a 1.6% sales slowdown in the last quarter -- and it's lowering 2014 projections.
What's the problem? It's simple -- their sandwiches (ironically) aren't big or good -- at least that's what the MarketSnacks team thinks. And so does this guy. Since customers aren't biting, the company is planning "new marketing and menu" strategies to keep up with fellow publicly traded fast-casual restaurant chains like Chipotle or Panera.
The takeaway is that Potbelly is now trading below its $14 IPO price. After its initial public offering in October, the stock price doubled as investors expected sales to keep up with its rapid store growth. No wonder CEO Aylwin Lewis called the quarter "disappointing."

3. Costco reports impressive sales jump
The 12 pounds of hamburger meat we bought before July 4th clearly had an impact on Costco's (NASDAQ:COST) bottom line. Shares of the sell-everything-bigger-and-cheaper chain rose 0.14% Thursday after announcing a 6% increase in June same-store sales above the 5.3% gain analysts had forecast.
The takeaway is that "same store sales" are a fun (and darn good) statistic for measuring a company's "financial health" because they include only locations open at least a year. And with a 7% rise in revenue from last year already, Costco is proving that it's already shaken off the winter weather blues that hurt most big U.S. retailers.
As originally published on MarketSnacks.com

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Jack Kramer has no position in any stocks mentioned. Nicolas Martell has no position in any stocks mentioned. The Motley Fool recommends Costco Wholesale. The Motley Fool owns shares of Costco Wholesale. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.