As recently as late December, Monsanto was named “company of the year” by Forbes magazine. Last week, the company earned a different accolade from Jim Cramer, the television stock market commentator. “This may be the worst stock of 2010,” he proclaimed. Add to Portfolio

Bags of Asgrow Roundup Ready soybean seeds sit inside a Monsanto lab in St. Louis. Monsanto, the world’s biggest seed company, plans to complete most of its $800 million stock buyback plan more than a year ahead of schedule after the shares dropped to the lowest since 2007.

Monsanto, the giant of agricultural biotechnology, has been buffeted by setbacks this year that have prompted analysts to question whether its winning streak from creating ever more expensive genetically engineered crops is coming to an end.

The company’s stock, which rose steadily over several years to peak at around $145 a share in mid-2008, closed Monday at $47.77, having fallen about 42 percent since the beginning of the year. Its earnings for the fiscal year that ended in August, which will be announced Wednesday, are expected to be well below projections made at the beginning of the year, and the company has abandoned its profit goal for 2012 as well.

The latest blow came last week, when early returns from this year’s harvest showed that Monsanto’s newest product, SmartStax corn, which contains an unprecedented eight inserted genes, was providing yields no higher than the company’s less expensive corn that contains only three foreign genes.