zeev,
when both the ratios of declining issues/advancing issues, and declining volumes/advancing volumes are similar, the trin would be near 1.
you would be surprised to know sept 17 - 21 week, despite huge sell-off, there was not a single day the trin was above 1.5
in fact, they were 1.37, 1.13, 0.91, 1.2 and 0.70 respectively.