Whole Foods Market (WFM) still can't grow its sales, a byproduct of what has become a ruthlessly competitive organic food market. 

The struggling organic grocer reported Wednesday that same store sales dropped 2.8 percent for the fiscal second quarter due to continued traffic weakness. It marked the fifth straight quarter of sales declines for Whole Foods. Things haven't gotten much better in the third quarter, either. Whole Foods said sales for the fifteen weeks ended Apr. 30 declined 2.5 percent as it battled its traffic issue.

Shares of Whole Foods climbed 3.6 percent to $37.60 in early trading on Wednesday, helped by earnings that came in line vs. Wall Street forecasts. The company also announced a board overhaul following pressure from activist investor Jana Partners.  

"Whole Foods has wasted years deliberating, analyzing, and deciding how to evolve in today's rapidly changing landscape, and given how much time has been wasted, we are far from convinced that there is enough of a sense of urgency to alter the trajectory under the current mgmt team," wrote Barclays analyst Karen Short in a new note. 

Said Whole Foods founder and CEO John Mackey on a conference call, "We need to do much more, much faster -- our competitors are not standing still."

Whole Foods founder John Mackey (right).
Whole Foods founder John Mackey (right).

"There remains an aggressive bear case on the stock, and this is reflected in the most recent short interest volume of 41 million," points out Pivotal Research Group analyst Ajay Jain, who rates the stock a sell with a $20 price target. "The upcoming results should provide a dose of reality regarding fundamentals."

The current short interest in Whole Foods represents about 13 percent of total outstanding share count.

Added Jain, "While recent declines in traffic have been alarming, it should be noted that comparable store sales would be much worse without the benefit of newer stores in the comp base."

Barclays analyst Karen Short, meanwhile, has estimated that Whole Foods, once an organic food pioneer, has lost a "staggering" nine to 14 million customer visits over the past eighteen months to grocery competitors like Kroger, Trader Joe's, Costco ( COST) , Sprouts Farmers Markets ( SFM - Get Report) and Natural Grocers ( NGVC - Get Report) .