Hey Lykkers, Let’s be real. How many times have you sat in a meeting or stared at a financial model and thought:

- “Wait…why are we assuming the growth rate will stay at 5%?”

- “Why do we think this customer behavior won’t change?”

- “Is the data source we’ve always used still the right one?”

You hesitate. It seems so basic. Someone must have already thought of this, right? Asking might make you look like you weren’t paying attention.

But what if that simple, “dumb” question is the smartest one in the room?

The High Cost of Unchallenged Assumptions

In finance, we build towering models on foundations of assumptions. Some are based on robust data, others on “the way things have always been done.”

The 2008 financial crisis, in part, happened because of an unchallenged assumption: that U.S. housing prices would never fall nationally. As behavioral finance expert Michael Mauboussin noted, “When most people come to believe the same thing, large gaps open up between price and value.” (The Success Equation).

The danger isn’t just in being wrong—it’s in not knowing you could be wrong. Your job as an analyst isn’t just to calculate; it’s to interrogate. The junior analyst who questions a base assumption isn’t naive; they’re doing one of the job’s most valuable tasks: stress-testing the foundation.

How to Spot an Assumption That Needs Questioning

Not all assumptions are created equal. Focus your energy on the ones that carry the most weight. Here’s a simple filter—question the assumptions that are:

1. The Key Driver: The one variable your model’s output is most sensitive to. Change it slightly, and does the entire conclusion flip?

2. The “Static” One: Anything described as “stable,” “consistent,” or “will continue at its historical average,” especially in a world that is demonstrably changing.

3. The Unexplained One: If no one can easily point to the source or rationale beyond “that’s what we used last year,” it’s a prime candidate.

The Art of Asking: Framing Your “Dumb” Question Smartly

You can’t just blurt out, “This is wrong!” The goal is collaborative inquiry, not confrontation. Master this simple three-part script:

1. Anchor in the Data/Goal: Start by aligning with the shared objective. “To make sure our model is robust for the investor presentation…”

2. Ask with Genuine Curiosity: Phrase it as a question, not a challenge. “…I was looking at the long-term growth assumption. Can you help me understand how we derived the 5% figure?” or “What would happen to our thesis if customer acquisition costs turned out to be 10% higher than we’ve modeled?”

3. Offer a Next Step (Optional but Powerful): Show you’re solution-oriented. “Would it be helpful if I ran a quick sensitivity analysis on that variable to see the impact?”

Your New Superpower

Lykkers, start today. In your next task, find one core assumption—just one—and trace it back. Ask, “What is this based on?” You’ll either strengthen your confidence in the model or uncover a critical vulnerability. Both outcomes are wins.

Remember, in a field built on predicting an uncertain future, the only truly dumb question is the one you were too afraid to ask. Your curiosity isn’t a weakness; it’s your professional edge. Now go find that invisible assumption.