Why short-term trading is counterintuitive

In

a recent post to my blog, I looked at strong 60-day periods in the market
and showed how it is not just the trend of price change, but its trajectory,
that leads for those moves to persist. This post will focus on short-term moves
of five days going back to 2004 (N = 697 trading days).

During that time, we’ve had 258 occasions in which the S&P 500 Index
(
SPY |
Quote |
Chart |
News |
PowerRating) has
been up over the last five sessions and up over the most recent session. Three
days later, SPY has averaged a loss of -.03% (130 up, 128 down). That is weaker
than the average gain of .09% (387 up, 310 down) for the entire sample.

When the previous five sessions have been up, but the most recent trading day
has been down (N = 133), the next three days in SPY average a gain of .04% (74
up, 59 down)–a bit weaker than average, but not so weak as the dual up periods.

When the previous five sessions in SPY have been down, but the latest day has
been up (N = 119), the next three days in SPY have averaged a gain of .15% (68
up, 51 down), somewhat better than average.

When the last five sessions are down *and* the most recent trading day is down
(N = 187), the next three days in SPY average a gain of .25% (115 up, 72 down),
handsomely above average.

These data fit nicely with the findings of Larry Connors and Conor Sen in their
book “How
Markets Really Work“, which found that returns are better after short-term
weakness rather than short-term strength.

The results also suggest that market returns are patterned in a
manner that is precisely the opposite from the pattern of human expectations.
If we see something rise during the past day and also during the past five days,
it is human nature to look for the trend to be our friend and continue into the
next several days. Conversely, if the market is down today and has been down
over the past week, we naturally consider the market weak and expect further
price softness.

But what happens is precisely the opposite.