Wash Sales : What order do losses attach to the cost basis of new purchases?

[Matt071021]

I have made several purchases of XYZ stock (across 2 brokers) within the +/- 30 day window of a loss sale (due to option expiring out of the money). what is the order of new shares that the new cost basis attaches itself to? 

Is it shares that I just purchased a week ago? 2 weeks ago? Can I just buy again today and my broker will adjust the cost basis for these shares and all other purchases will be ignored?

Thanks for any info!

[Corrlich44]

Great question Matt071021,

Your broker will automatically adjust the cost basis for any same or similar new purchase, the second a loss was initially being determined by their cost basis software.