Marc Grøndahl is a co-founder of Planet Fitness and the most credible estimate of his net worth sits at roughly $20 million, based on his publicly disclosed insider stock holdings and historical share transactions. That figure comes from CoreStreet, which pegged his equity-derived net worth at 'at least $20,280,059' as of March 12, 2026. If you fold in his other business interests, including his self-storage venture Bluebird Self Storage and any private assets not captured in SEC filings, the real number could be meaningfully higher.
Marc Grøndahl Net Worth: Estimate, Sources, and How It’s Calculated
Jordan Whitfield
2 May 2026
Which Marc Grøndahl Are We Talking About?
Before getting into the numbers, it is worth a quick disambiguation. The name 'Marc Grondahl' (with or without the ø) can surface a few different people online, and getting the wrong one is easy. The Marc Grøndahl this article covers is Marc E. Grondahl, the co-founder and former CFO of Planet Fitness, the gym franchise. He is listed by the BBB as a manager of Bluebird Self Storage and appears in multiple Planet Fitness SEC filings as a board member and beneficial owner. This is distinct from figures like Marc André Grondin, the Quebec-born actor, or other Marcs with similar names that show up across entertainment, finance, and business. If you are actually looking for the actor Marc André Grondin, his net worth figures follow a different public trail than Marc Grøndahl’s business holdings Marc André Grondin net worth. If you landed here looking for a different Marc, the search was close but the person is different.
Who Marc Grøndahl Actually Is
Marc Grøndahl graduated from Bryant College (now Bryant University) in 1988 with a degree in business administration. He spent a few years working as a cost accountant at a manufacturing company, which is about as unglamorous a starting point as you can imagine for someone who would eventually co-found one of the largest gym chains in the United States. In 1992, he and his brother Michael Grondahl launched Planet Fitness out of Dover, New Hampshire. What they built was a deliberately low-cost, judgment-free gym concept that turned out to be exactly what a huge segment of the American public wanted.
Marc served as CFO starting in 1998, overseeing the financial and strategic planning that helped Planet Fitness scale its franchise model across the country. He spent roughly 20 years inside the business, helping develop and refine the model from the ground up. He was named Chairman of the board in August 2010 and resigned as CFO on July 25, 2013, at which point he was no longer an officer or employee. He has continued serving on the board since November 2012, so he remains a formal part of Planet Fitness's governance structure even after stepping back from day-to-day operations. After leaving the executive role, he moved on to Bluebird Self Storage, a real-estate-adjacent venture that reflects a pretty classic post-exit path for operationally experienced founders.
What 'Net Worth' Actually Means Here
Net worth, in the most literal sense, is assets minus liabilities. For a private individual like Marc Grøndahl, nobody outside his accountant and maybe his estate attorney knows the true number. What sites like CoreStreet and GuruFocus actually calculate is a narrower proxy: the value of publicly disclosed stock holdings and insider transactions, pulled from SEC Form 4 filings. For a concise snapshot of the latest figures people are searching for, see the marc granet net worth estimate based on publicly disclosed equity holdings. That is a real and verifiable slice of wealth, but it is not a complete picture. It excludes private business equity (like his stake in Bluebird Self Storage), real estate holdings, cash, retirement accounts, and anything else that does not show up in a public regulatory filing.
This is why you will see wildly different numbers across different sites. GuruFocus, for instance, listed his net worth as 'at least $0' in early 2026, explicitly noting that their model assumes no transactions have occurred after January 13, 2017. If his disclosed share position was sold or transferred after that date and not captured in their model, the output drops to zero even if he is sitting on tens of millions in actual wealth. CoreStreet's methodology is more current, tying its March 2026 estimate to historical insider sale activity and current holdings, which is why their figure is more useful. Neither number is wrong exactly; they are just answering different questions.
The Current Net Worth Estimate and Range
The most defensible current estimate for Marc Grøndahl's net worth is in the range of $20 million to $35 million or more. The $20.28 million floor comes directly from CoreStreet's equity-based calculation as of March 12, 2026, anchored in his Planet Fitness insider holdings and disclosed transactions. The upper end of the range is a reasonable inference: Planet Fitness went public in 2015, and as a co-founder who spent two decades building the business, Marc's equity stake at and after the IPO would have been substantial. Founder investors like Marc are named in Planet Fitness's Tax Receivable Agreement, which structures ongoing financial benefits tied to the company's ownership mechanics, suggesting his financial relationship with Planet Fitness extends beyond just board compensation.
| Source | Estimate | As Of | Methodology |
|---|---|---|---|
| CoreStreet | At least $20,280,059 | March 12, 2026 | Insider stock sales and current holdings (Form 4) |
| GuruFocus | At least $0 | March 13, 2026 | SEC Form 4 insider data; assumes no transactions after Jan 13, 2017 |
| This site estimate (range) | $20M–$35M+ | May 2026 | CoreStreet baseline plus inferred private business and real-estate assets |
Where the Money Likely Comes From
There are three main buckets that plausibly drive Marc Grøndahl's wealth, and they are all traceable to varying degrees through public filings and news sources.
Planet Fitness Equity and Founder Stakes
This is the big one. Marc co-founded Planet Fitness in 1992 and stayed deeply involved for two decades. SEC filings confirm he holds beneficial ownership in Planet Fitness shares, and his name appears in the company's 2023 and 2026 proxy filings in beneficial ownership tables. He is also a named owner of PF Principals, LLC and PFP Direct Loan LLC alongside fellow co-founder Chris Rondeau, entities that provided financing to qualified Planet Fitness franchisees. His revocable trust, 'The Marc Grondahl Revocable Trust of 2006,' is named as a Founder Investor in the company's Tax Receivable Agreement, which is a formal mechanism that provides ongoing cash flows tied to tax savings generated by the company's structure. That kind of arrangement does not go away when you step back from the CFO chair.
Board Compensation
As a Planet Fitness board member since November 2012, Marc receives ongoing director compensation. Planet Fitness is a publicly traded company (NYSE: PLNT), and board directors typically receive a mix of cash retainers and equity grants. This is not founder-scale money, but it is a real and recurring income stream that shows up in proxy disclosures.
Bluebird Self Storage
After stepping away from Planet Fitness operations, Marc launched Bluebird Self Storage. Bryant University's coverage of his career identifies this as his next major venture, and the BBB lists him as a manager of the business. Self-storage is a notoriously cash-flow-positive real-estate sector, and operationally experienced founders often do well in it. The financial details of this business are private, so there is no precise way to assign a dollar value to his stake, but it is a reasonable source of additional wealth not captured in the equity-only estimates from CoreStreet or GuruFocus.
How Recent Moves Could Change the Number
Planet Fitness's stock price directly affects any equity-based estimate of Marc's net worth. If PLNT shares rise or fall significantly, the CoreStreet-style estimate moves with it. The 2026 proxy filing referenced in Planet Fitness's SEC documents includes updated beneficial ownership figures for Marc, so anyone tracking his wealth should treat that filing as the most current public data point available. Beyond stock price movement, any expansion or sale activity at Bluebird Self Storage could change the private-asset portion of the estimate, but that information would only become public if the business were sold, acquired, or filed for financing in a way that created a public record.
His tenure structure also matters for context. He stepped away from Planet Fitness operations in 2012 and 2013, so the income accumulation from his salary and bonus years is largely historical at this point. The ongoing drivers are equity appreciation, board compensation, and Bluebird. That means his net worth is less likely to spike from a new job announcement and more likely to track Planet Fitness's market performance and any private business exits.
How to Verify This Yourself and Spot Bad Estimates
If you want to check the numbers independently, the best primary sources are all public and free. Start with SEC EDGAR and search for Planet Fitness (ticker: PLNT) proxy filings (DEF 14A). Marc Grondahl's beneficial ownership figures appear in the ownership tables of these documents. The 2023 and 2026 filings both reference him directly. Form 4 filings, also searchable on EDGAR, show insider transactions and are the raw data that CoreStreet and GuruFocus use to build their estimates.
When evaluating third-party net worth claims about Marc Grøndahl (or any figure like Marc Grandisson, Marc Forgione, or others in business and finance), watch for a few red flags that signal a low-quality or outdated estimate: If you are specifically trying to understand Marc Forgione net worth, you should be careful to confirm which individual the sources are actually discussing before comparing any figures.
- No 'as of' date on the estimate: wealth figures without timestamps are almost always stale
- No stated methodology: if a site says '$X million' without explaining how they got there, treat it as a guess
- Round numbers with no source: '$30 million net worth' with zero supporting data is almost always fabricated or copied from another fabricated source
- Conflation with another Marc: double-check that the article is specifically about the Planet Fitness co-founder and not another person with a similar name
- Figures that ignore the GuruFocus caveat: GuruFocus's '$0' estimate is not evidence he is broke; it reflects a data cutoff issue, not actual wealth
The cleanest approach is to treat CoreStreet's March 2026 figure as a confirmed floor for his publicly disclosed equity-based wealth, layer in reasonable inferences about private assets and board pay, and follow future Planet Fitness proxy filings to track any changes in his disclosed share ownership. This aligns with what people often search for as Marc K Griffin net worth, using disclosed equity data as the base CoreStreet's March 2026 figure. That gives you a running estimate grounded in verifiable data rather than recycled blog speculation.
FAQ
How can I confirm I’m looking at the right Marc Grøndahl before trusting a net worth number?
Look for Marc E. Grøndahl tied to Planet Fitness proxy tables and Form 4 filings (ticker PLNT). If the results do not show beneficial ownership in Planet Fitness or his association with Bluebird Self Storage, you are likely seeing a different person with a similar name, and any net worth figure will not match the Planet Fitness-based calculations described in the article.
Why do equity-based net worth estimates sometimes drop even when the company’s stock price rises?
Equity-based models usually rely on beneficial ownership and insider transactions from SEC filings, so a sale can reduce the “headline” net worth even if his overall wealth stays the same. To interpret changes, check whether his Form 4 activity shows sales, gifts, or transfers after the model’s cutoff date, because that is what drives the estimate down or up.
Can I verify Marc Grøndahl’s Bluebird Self Storage stake value from public data?
Yes, but only indirectly through filings. If Bluebird Self Storage is private and there are no public securities filings for it, its value will not be captured. You typically infer it from public mentions, officer and manager listings, or any public record that shows financing, asset sales, or ownership changes.
What is the quickest way to independently update his net worth estimate using primary sources?
Use a “latest proxy then latest Form 4” routine. Start with the most recent Planet Fitness DEF 14A to see beneficial ownership at that time, then review subsequent Form 4 transactions to determine whether his shares were bought, sold, or transferred since the proxy date.
What does it mean when a site reports “at least $0” for Marc Grøndahl’s net worth?
CoreStreet-style figures are best treated as a floor or lower bound for publicly disclosed equity holdings. Other sites can show zero or near-zero when their model assumes no insider transactions after an old date, so you should compare the model assumptions, not just the displayed number.
Why can two estimates use the same share data but still disagree on the dollar value?
Proxy and Form 4 data are typically in terms of shares and ownership classifications, but the implied dollar value depends on the valuation date used by the estimator (often tied to stock price around the filing period). If you are comparing two sites, their valuation date and calculation method can create differences even with the same share counts.
Does board compensation materially change his net worth, or is it mostly a smaller, steady contribution?
Director compensation is usually smaller and more stable than founder equity gains, but it can matter for the “wealth-building over time” story. For current income, you would look at the compensation discussion and director compensation tables in the latest proxy, and note that those numbers reflect cash and granted equity in that year, not total net worth.
What events should I watch to predict whether his net worth estimate will change significantly?
Track the value-driving events rather than day-to-day noise. The biggest swings in an equity-only net worth proxy come from PLNT price changes and any disclosed share transactions. For private assets, you only see meaningful updates when there is a public event like financing, acquisition, or a transaction that creates a record.
What are the most common mistakes people make when comparing Marc Grøndahl net worth figures across websites?
Be cautious with “net worth” claims that come from entertainment-style pages or unrelated business people with similar names. The fastest sanity check is whether the source connects the person to Planet Fitness SEC disclosures and the same entities mentioned in the article (for example, founder investor arrangements and beneficial ownership references).
If I want to build my own reasonable range, what’s a simple calculation approach and what should I leave as an uncertainty?
If you want a practical estimate yourself, use the disclosed beneficial share count from the latest proxy as your base, multiply by a consistent PLNT share price on a specific valuation date, and then add a conservative buffer for private assets and non-stock holdings. The buffer should be treated as uncertain, because cash, retirement accounts, and private company equity are not captured in SEC stock-only models.
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