24 pages. Excerpt: Impact varies by account balance: This Issue Brief estimates changes in average 401(k) balances from Jan. 1, 2008, to Jan. 20, 2009, using the EBRI/ICI 401(k) database of more than 21 million participants. Not surprisingly, how the recent financial market losses affect individual 401(k) account balances is strongly affected by the size of a participant's account balance. Those with low account balances relative to contributions experienced minimal investment losses that were typically more than made up by contributions: Those with less than $10,000 in account balances had an average growth of 40 percent during 2008, since contributions had a bigger impact than investment losses. However, those with more than $200,000 in account balances had an average loss of more than 25 percent.