The typical blackout period lasts from 4 to 6 weeks and is imposed when an employer-sponsor of a 401(k) plan changes from one plan administrator to another. Claims against fiduciaries charged with overseeing such plans most frequently arise when the stock market falls sharply during blackout periods. Claims are more likely at such times, because employees are unable to transfer monies out of stocks and thus reduce losses. To reduce exposure to such claims, companies offering 401(k) plans should provide notice of blackout periods well in advance of the date on which they are scheduled to begin.