Investors loaded their shopping carts with shares of Whole Foods Market (NASDAQ:WFM) Wednesday, pushing the stock up more than 10% after the organic grocer posted stronger-than-expected fiscal second quarter results.

Let's dig deeper, then, to see what has everyone so excited.

Whole Foods Market Bird's Eye View, Whole Foods stock

Bird's eye view of a Whole Foods store, Image source: Whole Foods

The numbers
On one hand, revenue rose more than 13% from the year-ago period, to $3.03 billion, which was in-line with analysts' estimates. Diluted earnings per share, on the other hand, increased 19%, to $0.76, beating expectations, which called for earnings per share of just $0.73. In addition, comparable store sales grew an impressive 6.9% during the quarter, and gross margin increased five points, to 36.4% of sales, thanks largely to lower occupancy costs as a percentage of sales.

As usual, Whole Foods also boasted healthy cash flow and generated $287 million from operations, of which the company invested $109 million in capital expenditures. As a result, the company achieved $178 million in free cash flow during the quarter.

What's more, in addition to the $37 million cost of Whole Foods' dividend, shareholders' slice of the pie was increased further as the company repurchased $37 million in common stock, bringing total stock repurchases so far in fiscal 2013 to $63 million. When all was said and done in March, Whole Foods had $1.3 billion in cash and investments on its balance sheet, and $409 million remaining under its existing share repurchase program.

Steady growth
During the quarter, Whole Foods continued its methodical march toward 1,000 locations in the U.S., opening six new stores, and bringing its total number to 349 locations in 40 states and three countries. Going forward, management expects to open just four new stores in their fiscal third quarter, followed by 12 new locations in the fiscal fourth quarter.

Management also noted on the earnings conference call that their 23 comparable stores less than two years old produced record returns on invested capital of 19%, showing just how effective the company has been at creating shareholder value by reinvesting capital in the business.

Raised guidance
Thanks to the relatively strong comparable store sales growth to date, Whole Foods management proceeded to raise both ends of the company's diluted EPS guidance by a few pennies, telling investors to expect fiscal 2013 earnings to now come in between $2.86 and $2.89 per share.

For all the good news that Whole Foods investors received this week, there remains one big concern worth noting.

Remember, both industry titans like Safeway, and fellow organic grocers like The Fresh Market are doing everything they can to win consumers' grocery dollars in today's strained economic environment. It shouldn't come as a surprise, then, that Whole Foods management reiterated they haven't changed their long-term strategy of pursuing more value-oriented items in an effort to increase their appeal to the masses.  As a result, they warned investors that year-over-year gross margin improvements won't be quite as impressive in the back half of the year.

Foolish final thoughts
Even so, while I'm certainly happy with the gains resulting from my decision to add Whole Foods stock to my personal portfolio last month, that doesn't mean I'll be taking profits anytime soon. To the contrary, I'm convinced investors would be wise to remember that Whole Foods' long-term growth story remains firmly intact, and it's not too late to buy a piece of this shareholder-friendly business.