And plaintiffs are armed with the U.S. Supreme Court's June decision in Fifth Third Bancorp v. Dudenhoeffer, which found that when a fiduciary's decision to retain company stock as an investment option is challenged in court, the fiduciary is not automatically entitled to a "presumption of prudence," but instead is subject to the same duty of prudence that applies to ERISA fiduciaries in general. 

Now, RadioShack's participants claim the plan fiduciaries should have known that investment in company stock was imprudent because of the "sea-change in the central risk/profile and business prospects of the company caused in part by corporate mismanagement," according to court documents. 

Plaintiffs claim the shift away from RadioShack's bricks-and-mortar model and the deterioration in demand for its products ultimately led to the collapse of the stock price and increased the risk of bankruptcy. 

RadioShack shares have been trading at less than $1 for about a month. In 2010, its high approached $25 a share. At the end of 1999, it was trading at about $77 a share. 

According to the court documents, RadioShack's fiduciaries also failed to provide participants the necessary available information to make informed decisions regarding the company's stock. While plaintiffs are not alleging the stock price was artificially inflated, they do claim the failure to disclose complete information mislead participants. 

"Given the totality of circumstances prevailing during the class period, no prudent fiduciary would have made the same decision to retain the clearly imprudent RadioShack stock as a plan investment," the plaintiffs' attorneys wrote. 

The company's 2009 Summary Plan Description explained that the company matched participant deferrals up to 4 percent of salary, and that the match could be made in the form of cash or company stock. 

Court documents show that one plan increased its holding in company stock as the stock priced crashed. For plan-year ending June 30, 2011, the company offered 24 investment options, including RadioShack stock. Some options were removed or added over the next two years, but the RadioShack option remained. 

As of June 30, 2011, the plan held 2.9 million shares of company stock valued at the time at $39.5 million. By June of 2013, it held more than 3.5 million shares valued at $11.25 million. 

Last week, Bloomberg News, citing an internal company memo, reported RadioShack will cease matching contributions in its retirement plans on Feb. 1, 2015, in an effort to avoid bankruptcy. 

The electronics retailer has lost money in each of the last 10 quarters.