Diamond Foods said Tuesday that it would miss its fiscal first-quarter filing deadline because of an ongoing investigation by its own audit committee into how the company accounted for payments to walnut growers.

Diamond, the maker of Emerald nuts, Kettle chips and Pop Secret popcorn, said it anticipated conclusion of its investigation by February. The announcement sent shares down in early morning trading.

The announcement came as a surprise to the market, which saw the company's shares surge 53 percent on Friday after an analyst wrote that he expected to see the investigation come to a quick end, with a finding of no evidence of wrongdoing.

In a release, Diamond said it expects to receive a note for a lack of compliance with the Nasdaq Listing Qualifications Department, but it will still be able to trade on the market.

Diamond will take steps to file its Form 10-Q for the first quarter as soon as practicable after conclusion of the investigation, the release read.

From the beginning of November to the market's close last Thursday, Diamond shares had dropped 59 percent. The company reached an all-time high in September, and shares on Thursday were down 72 percent from that level.

The crash built from two events. One is the investigation, which deals with what the company calls momentum payments. Some shareholders have filed suit against Diamond, saying the company tried to mislead them with better earnings reports by moving costs from the end of its fiscal year 2011, which ended in July, to the 2012 fiscal year.

The other is the November suicide of board member Joseph Silveira. Police did not reveal any motive, but a Diamond spokesman told Reuters that any thought of a connection between the investigation and Silveira's suicide was unfounded.

On Friday, though, Diamond shares climbed back, skyrocketing nearly 53 percent. That was the result of a report released by KeyBanc Capital Markets analyst Akshay Jagdale, who opined that the investigation would end swiftly and without much consequence for the company.

Diamond is in the process of a $2.35 billion acquisition of the Pringles brand from Procter & Gamble. On Nov. 1, the company said it would delay that acquisition from its planned December close to the first half of the 2012 calendar year.

In his report, Jagdale said the cost from Diamond's investigation is unlikely to affect the company's acquisition of Pringles.

As of 11:30 a.m., shares were down just more than 1 percent.