Donchian's Four-Week Rule . SPX_W stockcharts.com/c-sc/sc?s=$SPX&p=W&st=2012-03-05&en=(today)&i=p65147369477&a=274919925&r=199 . RUT_W stockcharts.com/c-sc/sc?s=$RUT&p=W&st=2012-03-05&en=(today)&i=p29919327567&a=274919926&r=387