Learn the terms · Longer read
Volume spikes: when far more shares than usual change hands
Volume is the number of shares that changed hands in a day. A volume spike is a day with far more trading than usual - on Trendentum, at least 1.5 times the 20-day average, that day included. Chart-watchers read it together with which way the price moved; Trendentum's figure shows the multiple only.
What it measures
Every trade has a buyer and a seller, so volume is not a measure of demand or supply on its own; it is a measure of activity. A stock that normally trades two million shares a day and trades five million has had a day when far more holders decided to act. Something made a lot of people move at once - a result, a broker note, an index change, news about a competitor - and volume records that it happened even when the price barely moved.
Trendentum compares each day's volume with the average of the last 20 sessions, that day included. At least 1.5 times that average is a spike; the methodology page states the multiplier, and your strategy settings can change it for this chart figure. The figure gives the size - "2.10x the 20-day average" - because 1.6x and 4x are different facts.
Why the direction matters
A spike on its own is ambiguous. Heavy trading while the price rose says the buying was insistent enough to absorb everyone who wanted out and still lift the price - conviction behind the rise. Heavy trading while the price fell says the reverse. Heavy trading with the price flat says two determined crowds met in the middle. That is why chart-watchers look at what the price did on the spike. Trendentum's figure does not say: it gives the multiple only, and that day's price bar is on the chart.
What a spike has historically been useful for is context on other rules. A moving-average cross on a quiet day is a few trades nudging a thin stock; the same cross on three times normal volume happened with a crowd behind it. Until 8 October 2026 volume was one of five rules behind the outlook; it is now a chart figure with no vote, and the backtester does not score it.
What it is not
Volume does not tell you who traded or why. Institutions rebalancing, an index fund adding the stock, options expiring and a founder selling down all look the same in the daily figure. A spike also says nothing about the following weeks - conviction on the day is not persistence afterwards, and plenty of busy days on a rising price have been followed by a lower one.
Nor is a low-volume day a signal of its own. Most days are ordinary, and the figure simply reports a multiple near 1; that is the honest reading.
An example
A stock that has averaged about 800,000 shares a day trades 2.4 million while rising 6% on the day of a contract announcement. Because the 20-day average includes that day, it rises to about 880,000, and the chart figure reads about 2.7x. A week later 1.9 million shares trade with the price down 4% after a broker downgrade; the figure reads about 2.0x. The multiple alone says "busy" both days; the price bars on the chart show which way each day went. Neither day changes the outlook.
Where you’ll see it on Trendentum
- Each stock's "Chart figures (no vote)" - the day's volume as a multiple of its 20-day average
- The price chart on each stock page, with each day's volume drawn
- The methodology page for the exact multiplier
Every term on this page is used the same way across the app, and the exact settings behind each chart figure are on the methodology page. Trendentum explains every call and never tells you what to do with it.