How to Scalp a Market
To scalp a market, calculate your exact round-trip cost first and require every target to exceed it by a meaningful multiple. Trade only the most liquid instrument in the busiest hours, because the spread is paid on every attempt and it decides the whole result.
Scalping is the only style where the transaction cost is larger than the thing being predicted. That single fact determines every step below, and it is why the arithmetic comes before the chart.
Before you start
Your exact round-trip cost per contract or share. Commission both ways plus the spread, in the units you trade. Not an estimate — the real number from a filled order.
The instrument with the tightest spread you can access. Scalping a wide-spread instrument is arithmetically hostile before you have formed a single opinion.
A target that clears the cost before it clears zero. Written down as a multiple of the round trip. If you cannot name that multiple, there is no strategy to test yet.
The steps
1. Calculate the round trip before anything else
Commission in, commission out, plus the spread you actually cross. On the shared price series this comes to 2% of a median bar’s range, and every attempt pays it.
2. Set the minimum target as a multiple of that cost
Three times the round trip is a defensible floor. Anything the market will not reliably deliver at that distance is not a scalp, whatever it looks like on the chart.
3. Trade only the tightest-spread instrument available
The most heavily traded contract or the largest listed name. Volume is not a preference here; it is the difference between a viable cost base and an impossible one.
4. Restrict yourself to the busiest hours
The open and the overlap between major sessions. Outside those windows the spread widens and the movement shrinks, which reverses the arithmetic in step two.
5. Account for the spread on every single attempt
Not on the winners. On all of them. A method taking 40 trades a day pays this 40 times regardless of how many worked.
6. Place a tight stop and expect it to be hit
A close stop is what makes the small target viable. It also gets touched frequently by ordinary movement, and a high loss count is the expected outcome rather than a fault.
7. Give it full attention or do not start
No second screen, no other task. The decision windows are seconds long and a distracted scalp becomes an accidental swing trade at the wrong size.
8. Record every trade, because the sample is the only evidence
At this frequency, memory is worthless and the record is the entire instrument. Log cost, session and result on every line.
How to tell it worked
Judge it at 100 trades, and no earlier.
Calculate the total cost paid across those 100 trades. Multiply your round trip by 100 and put that figure next to the gross result. If costs exceed the gross, the strategy is a fee-generation machine and no entry improvement will fix it.
Count the trades taken outside your chosen hours. The acceptable answer is 0 out of 100. Session discipline is the cheapest edge available in this style and the first one abandoned.
Then check the average winner against your minimum target. If the average win is below the 3x round trip from step two, the targets are being taken early, and the arithmetic the method was built on is not the arithmetic being traded.
Why the arithmetic decides this before the chart does
The measured cost on this site’s shared series is 2% of a median bar’s range per round trip, and it reaches over 10% on 15 of 576 bars. That is the whole problem stated numerically: on the quietest bars, a round trip consumes a tenth of everything the bar offered.
Direction runs average 2.01 bars with the longest at 11. So the moves a scalper is trying to catch are, on average, two bars long — and the cost of participating is a fixed toll paid at the start of each one.
Which is why the style tolerates no asymmetry in the tail. A single adverse gap or headline can erase a hundred small wins, because the wins were capped by design and the loss was not.
The original data
Of the 24,971 unique videos in research/search-study-corpus.jsonl, 67 have an instruction-shaped
title mentioning scalping, at a median of 32,337 views across 55 channels, with a maximum of
1,220,619. Day trading appears in 316 instructional titles at a median of 36,138. The counts come
from site/rank_howto.py.
Sixty-seven videos across 55 channels is a well-covered subject with an unusually high median. It is one of the few topics in this corpus where high supply and high demand coexist, which suggests genuine sustained interest rather than a passing trend — and it makes the cost arithmetic the only thing left to differentiate on.
The answer to the question on that chart is that one tick does not cover the round trip. A winner taken below the cost threshold is a losing trade with a green number on it, and the habit of banking small positives is the most common way a scalping record ends up negative while feeling successful.
When it fails
A quiet market is where this style dies, and it dies invisibly. Spreads widen while ranges shrink, so the cost per attempt rises at exactly the moment the available movement falls. Nothing dramatic happens — the account simply grinds down through a series of trades that each looked reasonable, and the damage is only visible in the record at the end of the month.
The second failure is scalping a wide-spread instrument. The arithmetic was lost before the first trade.
A third is taking profits below the cost threshold. Green does not mean profitable at this frequency.
A fourth is trading outside the chosen hours. It reverses the cost-to-movement ratio the method depends on.
A fifth is widening the stop after a loss. It removes the only thing making the small target viable.
And a sixth is judging it on fewer than 100 trades. At this sample size the noise is larger than any edge could be.
Related
Scalping covers what the style is and what it demands of the person doing it. Bid-ask spread is the cost that decides whether any of this works. And day trading is the broader category, with more room for the cost arithmetic to be survivable.
I ran the arithmetic on this before I ran the strategy, which is the only reason I stopped. At a few hundred trades a month the round trip was consuming more than the edge I thought I had, and no amount of improving the entries would have closed that gap. Scalping is the one style where the spreadsheet answers the question before the chart does.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.