Shares of Whole Foods Market tumbled in after-hours trading on Wednesday after the grocery chain reported a revenue shortfall in its fiscal fourth quarter and trimmed its annual outlook for 2014.

Shares were down more than 9 percent in after-hours trading even as the food chain, known for its organic and natural food offerings, posted a 7 percent increase in profits, helped by lower food inflation.

The latest results show that Whole Foods Market Inc., which based in Austin, Texas and has more than 350 locations, is facing a more competitive landscape. The chain has been able to boost sales in large part because its health glow fits with changing eating habits. But more mainstream players are increasingly tapping into that trend as well, and rolling out more products or sections labeled as natural or organic.

Whole Foods is also battling a perception among shoppers that its food is pricey and instituted a round of price cuts to lure shoppers.

Whole Foods earned $121 million, or 32 cents per share, in the three-month period ended Sept. 29. That compares with $113 million, or 30 cents per share, in the year-ago period.

Revenue rose 2.2 percent to $2.98 billion, from $2.91 billion a year ago.

Analysts, on average, expected 31 cents on revenue of $3.04 billion, according to FactSet.

The company said that its sales rose 5.9 percent at locations open at least a year. That was slower than the 7.5 percent gain in the third quarter and lower than the 8.5 percent gain from a year ago.

Whole Foods also told investors during a conference call Wednesday that it saw sales being cannibalized, particularly in Boston where it opened five new stores in the fourth quarter alone. It also cited tough competition and overall pressures from the economy.

Against this difficult climate, Whole Foods now expects sales at stores opened at least a year to be up 5.5 percent to 7.0 percent for the year. That's scaled back from its original guidance for 6.5 percent to 8 percent. The figure is an important gauge of a retailer's growth, because it measures growth at continuing locations rather than at newly opened or closed stores. Whole Foods opened 12 stores during the quarter.

The company also now expects total sales to be up 11 percent to 13 percent for the year, instead of its original prediction for 12 percent to 14 percent.

As for its earnings predictions, it now expects earnings per share to rise 12 percent to 15 percent, to a range of $1.65 to $1.69 per share. That compares with the original outlook of $1.69 to $1.72 per share.

Analysts expected $1.73 per share, according to FactSet estimates.

During the conference call with investors, Whole Foods said it was "prudent to take a more conservative point of view" in its sales and earnings outlook for the year.

Whole Foods shares fell $6.12 to $58.35 in after-hours trading after the stock climbed 78 cents to $64.47 during the regular session. The stock is up 41 percent since the start of the year.