The Shanghai Food and Drug Administration concluded its investigation into chicken sold by Yum Brands' (YUM) KFC stores in China on Jan. 25, the company said in Monday's fourth-quarter earnings release. The Chinese agency did not fine the company or decide to bring a legal or regulatory case for higher-than-permitte​d levels of antibiotics in chicken sold by KFC from supplier Liuhe Group.

That doesn't mean that investors, though, have cleared the company. The stock fell 1.99% Monday before the earnings report and then another 5.38% in after-hours trading for a total loss on the day of 8.2%.

The problem wasn't fourth-quarter earnings -- the company actually beat expectations by a penny -- or revenue, which at $4.15 billion was slightly ahead of the $4.12 consensus. But then the company had already radically lowered guidance on Jan. 7. On that date, the company said the discovery of high levels of antibiotics in chicken sold by KFC had crushed sales in China in the last two weeks of December.

It was guidance for the first quarter and indeed all of 2013 that hurt. Same-store sales in China are likely to fall by 25% in January and February, the company said Monday. Company-wide earnings will fall in 2013 from $3.25 a share in 2012, the company noted. That was a huge shift from previous guidance for 10% earnings growth. Wall Street had been forecasting 2013 earnings of $3.57 a share. Investors should expect a significant drop in same-store sales in China during the first half of 2013, the company said, with a return to growth in China in the fourth quarter of 2013. Yum Brands got about 44% of 2011 revenue from China.

The restaurant operator had a 24% increase in same-store sales in India, its next big growth target. But same-store sales in other regions just matched analyst projections. Same-store sales climbed 3% in the United States and 3% at international stores. Analysts had been expecting 3% growth in the United States and 3.9% growth internationally.

My conclusion is that Yum Brands Monday turned into a second-half of 2013 story -- assuming that the company moves aggressively to rebuild the trust of Chinese consumers.

So far, at least, the company has not scaled back plans to open 700 new stores in China this year. It is planning to launch a campaign in China that emphasizes brand quality. And Yum Brands has already adopted the recommendations of China's state Food and Drug Administration to strengthen controls in its poultry supply chain by voluntary self-testing, better supplier management and improved reporting.

I'd like to see how much impact -- and how quickly -- those measures have on sales in China before I pick up shares of what is still the dominant fast-food restaurant business in China. At the moment, though, investors don't know when that unit will return to growth.

At the time of this writing, Jim Jubak didn't own shares of any companies mentioned in this post in personal portfolios. The mutual fund he manages, Jubak Global Equity Fund (JUBAX), may or may not own positions in any stock mentioned. For a full list of the stocks in the fund as of the end of the most recent quarter, see the fund's portfolio here.