In the above chart, I have plotted the PowerShares QQQ Trust (QQQ), the ETF that tracks the Nasdaq 100, versus the Nasdaq 100 A/D line. The A/D line made sharp new lows in November, as did QQQ before it rebounded back to the $31.63 level in both December and January (line d). The March 9 lows in QQQ at $25.63 were just above the November 2008 lows at $25.06.
Though it is tough to tell on the chart, the Nasdaq 100 A/D line did make slightly lower lows in March. It had tested its downtrend from the June 2008 highs in February (see circle) but failed to move through it. The A/D line rose sharply from the lows and broke its downtrend on March 23.
By early April (line 1), the A/D line was in a new uptrend, as tests of its weighted moving average were well supported. Further resistance for QQQ at $33.85 was overcome by the end of April, which was confirmed by the A/D line.
Both QQQ and the A/D line formed corrective flag patterns in July before both again moved sharply higher. The A/D line stayed positive and held support (line e) and by April 2010, QQQ had moved above the $50 level.