The SIM Series
(Dan Goldberg, Head of Risk)
I find this subject fascinating. And for over 20 years in this industry, the fundamental difference between trading SIM and LIVE has not changed a single iota.
I am going to split this into a series of articles because the subject is just too extensive to cover in one part. Plus, it’ll keep you coming back for my absolute gold!
I saw someone recently ask about SIM and LIVE, “How is this performance change possible?” It seemed a naive question to me. But it got me thinking. Well, why? Enunciate it. Put it down, lay it out, and then perhaps we can work through a structure of how to change the dynamics of it.
That is our challenge.
But seriously, I have seen this for years. I always remember one certain trader, bless him, who stayed with my firm for years. He holds the record, by a mile, for the longest time on the SIM! Nearly 2 years! Every single day, he posted good numbers on SIM, but the second he went LIVE, it was the polar opposite. Endless days of losses. Back on SIM… winners. LIVE….. Loss after loss. Eventually, he had to move on, but he highlighted the shift in environment more than anyone I can remember.
He’s not alone. It still happens today. People who can shift around on SIM effortlessly, struggle LIVE. SIM is useful, by the way. It allows structured practice without capital at risk. But that is all it does. Any track record built around SIM is largely meaningless.
So why the chasm of difference?
Risk Is The Primary Variable
In SIM, losses are informational. In LIVE trading, losses are financial and reputational.
Even if position sizing is small, the presence of actual capital at risk changes:
- Cognitive load
- Emotional response
- Decision latency
- Risk perception
Under LIVE conditions, the amygdala is engaged. Loss aversion and outcome bias influence execution quality. Traders often discover that strategies that seemed statistically stable in SIM become difficult to execute consistently when real capital is exposed.
The difference is not technical—it is neurological.
Order Execution Is Not Identical
TT is by far the closest you will get to it, but even so, it cannot replicate a live market perfectly. When we switched over to TT, I did notice that some traders who had been having excellent runs on prior software were now struggling due to the clever way TT replicates LIVE fills in terms of queue positioning and such.
It can’t, however, be perfect. Why? Because when you actually trade live, you are changing the market. Even in small size, it makes a difference. The market simply cannot be the same because you are changing it through your interaction.
This discrepancy becomes more visible in:
- Scalping strategies
- High-frequency entries
- Tight stop systems
- News-driven volatility
Psychological Capital Is Not Modeled
In LIVE trading, capital is not only financial. It is psychological.
Drawdowns affect:
- Confidence
- Risk tolerance
- Aggression level
- Pattern recognition bias
After a 5R drawdown in SIM, traders often continue with neutral cognition.
After a 5R LIVE drawdown, risk perception typically shifts.
This changes trade selection quality.
SIM does not deplete psychological capital. LIVE trading does.
Incentive Structures Differ
SIM performance is rarely audited by consequence. LIVE performance carries consequences:
- Personal financial impact
- External evaluation (if trading prop)
- Performance pressure
- Self-identity implications
The presence of consequence alters behavior. Traders become either:
- Overly defensive
- Prematurely aggressive
- Outcome-fixated
SIM performance is informational. LIVE performance is existential.
Time Perception Distorts
In SIM, a 2-point adverse move may feel technical. In LIVE, the same move feels temporal—slower, heavier.
This subjective time distortion impacts:
- Stop movement decisions
- Exit discipline
- Reversal tolerance
Neuroeconomics research consistently shows that perceived time expands under financial threat. SIM rarely triggers this effect.
Commitment Level Is Lower in SIM
Subconsciously, SIM trades are reversible in narrative terms. You can also just hit the mental “reset” button. A fresh start with no lasting consequences.
Traders are more likely to:
- Skip journaling
- Deviate from plans
- Experiment impulsively
- Ignore small rule breaks
LIVE trading exposes the cost of small deviations.
SIM allows hypothetical discipline. LIVE demands enforced discipline.
Identity and Ego Interference
SIM results do not threaten identity.
LIVE losses can conflict with:
- Self-perception as a “good trader”
- Social image
- Career trajectory
This identity friction alters risk-taking and accountability. On SIM, you can kid yourself that you were just playing on that trade.
Capital Constraints Change Strategy Viability
In SIM, offside is theoretical.
Strategies that rely on “statistical recovery” or “mean reversion” may appear robust in SIM but become impractical under LIVE capital constraints.
This concept, for me, is by far the most visible on my screens. I see it all the time. Next week, I want to go through this in detail before we attempt to navigate the issues outlined above. I see it regularly, I hate it, and I have argued over this topic time and again.
But for now, the takeaway is this:
SIM to LIVE
The strategy may remain identical.
The operator does not.
Dan’s Weekly Wisdom:
“Transition failure is rarely about edge. It is usually about adaptation.”