I own stocks that became worthless in 2009 but I forgot to enter them in my 2009 tax return as a capital loss (purchase price was about $4K in 2007).

The IRS website says you can amend capital losses from worthless securities within 7 years of the loss:
Publication 17 (2012), Your Federal Income Tax

For the tax years of 2009 - 2012 it did not matter since I did not have any significant net capital gains. However, for the 2013 tax year I do expect to have a capital gain. Can I amend my 2009 return and then somehow carry over the loss all the way and use it in 2013?

Thank you!