It’s Not a Lie if You Believe It

Author: MBI Deep Dives URL: https://www.mbi-deepdives.com/its-not-a-lie-if-you-believe-it/ One-line: A portfolio manager recounts selling his entire Canada-based portfolio to consolidate assets in the US ahead of a cross-border move, watching the stocks rally ~10% right after, and coping by pretending — for disclosure purposes — that he never sold at all.

Key claims

• A forced sale for tax/logistics reasons cost the author ~1,000 bps of portfolio performance. He expected to gain or lose ~200-300 bps moving assets from Canada to the US, but ended up “losing” roughly 1,000 bps during the transition window.
• Meta (Company) rallied ~10% on a Bloomberg report that it planned a cloud business to sell excess AI compute — news the author argues shouldn’t have moved the stock, since Mark Zuckerberg had already signaled this intent on Meta’s Q3 2025 earnings call (“if you got to a point where you overbuilt, you could have that as an option”).
• Short-term stock moves are mostly noise (“Brownian motion”). The author frames the market reaction to the Meta report as evidence that many investors had wrongly assumed Meta would just hoard excess compute rather than monetize it.
• Nearly his entire former portfolio (Meta, Veeva, Ryan Specialty, Airbnb, Floor & Decor) rallied 8-25% within a couple of weeks of him selling, with no clear fundamental catalyst.
• He decided to buy back most of what he sold, excluding Veeva and Ryan Specialty (which he may repurchase later), and chose to treat the whole episode as if he’d held the positions all along for his own disclosure/psychological accounting — explicitly likening it to a “Costanza” move (referencing the Seinfeld line “It’s not a lie if you believe it”).
• The piece argues for staying out of the day-to-day tape if an investor has the luxury of a long time horizon, rather than being “slave to your screen.”

Notable quotes

“I know that’s a lie, but please allow me to believe this lie to psychologically deal with the eyewatering money I have lost in the ether. I know I’m pulling a Costanza here.”

“If anyone leans to form their opinion based on short-term stock price movements, this market can make such investors increasingly insane. If you have the luxury of investing for the long-term, I suggest you take such opportunity with both hands and save yourself from the daily Brownian motions of the stock market.”

“…any compute that we don’t need for that we feel pretty good that we’re going to be able to absorb a very large amount of that to just convert into more intelligence and better recommendations in our family of apps and ads in a profitable way… Like almost every week, people come to us from outside the company asking us to stand up an API service or asking if we have different compute that they could get from us and we haven’t done that yet. But obviously, if you got to a point where you overbuilt, you could have that as an option.”

How it connects

• MBI Deep Dives — author’s Substack, a long-running Deep Dives / daily-journal investing publication.
• Mark Zuckerberg — quoted from Meta’s Q3 2025 earnings call on excess AI compute.
• Meta (Company) — the stock whose ~10% rally on the compute-monetization report anchors the piece’s argument about market noise.