DOW theory gives three signals for the end of a market. Dow wrote that:
a market moves up with higher highs and higher lows. At some point, it makes a high but, on the retracement, breaks the trendline. This is signal No. 1.
Then, market makes a high at or near the previous high but this high is below the trendline. This is signal No. 2.
Then, the market makes a new low that takes out the previous, intervening low. This is signal No. 3.
The new trend is established ---- and it's down. This gives you three more signals and a darn good reason to get out!