Youssef Boudlal / Reuters The morbid joke about the Great Recession was that it turned Americans’ 401(k)s into 201(k)s. Indeed, the nation’s 401(k)s and IRAs lost about $2.4 trillion in the final two quarters of 2008, and the average loss that year for workers who had been on the job for 20 years was, according to one estimate, about 25 percent.