In this case, the momentum was positive, so the price trend was up, but as the market rose, momentum fell. Conventional momentum analysis plots the change in price for some arbitrary length of time coincidentally with price itself. On the fifth day, the five-day momentum reading is zero. On the sixth day the market closes at 101, and an uptrend begins. Thereafter, the market continues to rise one point per day.
Buyers are strong.
If the market continued to rise, the trend would be considered stronger because the buyers managed to maintain one-point gains for a longer period. When a price trend is longer than the momentum line's period length, the strength of the trend is understated. In addition, when the number of days in a trend is shorter than the momentum line's period, the strength of the trend can be overstated. For example, if an uptrend began five days ago and you are using a 20-day momentum line, the latest momentum reading will not solely reflect the strength of the new trend. The reading would be a function of the five-day trend, plus the price change of the prior 15 days.