What happened

Shares of Conagra Brands (CAG -0.61%) fell 34% in December, according to data from S&P Global Market Intelligence, after the packaged-foods company announced mixed quarterly results and disappointing forward financial guidance.

After drifting lower for the first three weeks of the month along with the broader market, Conagra stock plunged more than 17% on Dec. 20 alone, after its fiscal second-quarter 2019 results hit the wires.

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So what

On one hand, Conagra's net sales climbed 9.7% year over year, to $2.384 billion -- a figure aided by its late-October acquisition of Pinnacle Foods, as organic sales declined 1.6%. Still, Conagra's top line technically fell short of Wall Street's average prediction for revenue of $2.41 billion.

On the other hand, adjusted earnings from continuing operations climbed 21.8% year over year to $0.67 per share, handily beating expectations for $0.55 per share.

Regarding the top-line shortfall, CEO Sean Connolly explained that the legacy Conagra Brands business reflected "continued momentum" during the quarter, with sales mostly in line with expectations. But the newly acquired Pinnacle business saw sales arrive below expectations because of "weak performance across a range of significant brands," as well as a product recall involving Pinnacle's Duncan Hines brand. 

Now what

That said, Connolly also insisted that after an "intense diagnostic," the company believes the source of Pinnacle's underperformance is "clearly executional, not structural, in nature."

As such -- and with the caveat that it will take time to implement -- Conagra is confident it will be able to translate its own best business practices to revitalize growth and make the most of Pinnacle Foods' portfolio.

Until Conagra can demonstrate more tangible progress to that end, however, I suspect the stock will remain under pressure.

Check out the latest Conagra earnings call transcript.