EURUSD breaks above 1.0900 on a Tuesday afternoon and runs 35 pips in fifteen minutes. Two hours later, Nasdaq breaks above 19,000 and runs 150 points in a similar window. Both charts show the same clean breakout candle. Only one of those two numbers tells you, directly, how many real participants were on the other side of the move. The other is an estimate wearing a real number's clothes.
That gap exists because forex and indices are built differently underneath the chart. Forex has no single exchange recording every trade, so no platform can show true traded volume for a currency pair. Indices trade through centralized exchanges that report every contract, so an index chart's volume figure is real. Knowing which kind of volume sits under your chart, and what it can and cannot prove, is most of the skill here.
Tick volume is a headcount, not a size count
The volume histogram under a EURUSD chart on most retail platforms is tick volume, a count of how many times the price changed within that bar, not the size or number of contracts traded. It correlates loosely with genuine activity, since more real trading tends to produce more price changes, but it stays an approximation. Treat a tall tick volume bar as evidence that something happened, not as proof of exactly how much money moved.
Real volume on indices carries more weight
Nasdaq and other index instruments trade through exchanges that report actual contracts changing hands, so the volume bar under an index chart is a genuine count. That is why volume reads are more trustworthy on Nasdaq or gold futures than on a forex pair, and why professional volume tools get used more confidently on the instruments that actually report size. The logic of confirming a move with volume applies to both markets. The reliability of the number underneath it does not.
A breakout worth trusting on Nasdaq
Say Nasdaq breaks above 19,000 on a 5 minute candle and closes at 19,040. Before trusting the move, compare that candle's volume to the simple 20 bar average volume on the same chart. A breakout bar printing at 2 to 3 times the 20 bar average shows real participation behind the push, and continuation is the more likely path from there. A breakout bar printing below the 20 bar average, on a thin candle with a long wick, is a move with few real buyers behind it, and it fades back inside the prior range far more often than it holds.
The empty move gives itself away first
Watch for price grinding to a new high while each successive bar's volume shrinks. On EURUSD that might look like price ticking from 1.0910 to 1.0925 to 1.0938 over three hours while tick volume falls on each leg. Fewer participants are pushing the move each time it advances, which is the classic exhaustion signature. It does not tell you when the reversal starts. It tells you the move is running low on fuel, which is a reason to tighten a stop or skip adding to a position, not a reason to short into strength.
What volume cannot do
Volume confirms. It does not predict. It is a lagging read on participation that already happened, and it works best in a trending or breakout regime where genuine participation and price direction move together. Inside a tight, quiet range, volume bounces around without telling you much about direction, because low volume in a range is normal, not a warning. Use volume to grade a move you are already watching, never as the reason to enter one on its own.