John Cox - Net Worth and Insider Trading
John Cox Net Worth
The estimated net worth of John Cox is at least $17 Million dollars as of 2026-08-10. John Cox is the CEO & President of Dyne Therapeutics Inc and owns about 440,151 shares of Dyne Therapeutics Inc (DYN) stock worth over $12 Million. John Cox is the EVP Pharmaceutical Oper & Tech of Biogen Inc and owns about 25,567 shares of Biogen Inc (BIIB) stock worth over $5 Million. John Cox is also the Director of Repligen Corp and owns about 923 shares of Repligen Corp (RGEN) stock worth over $150,463. Details can be seen in John Cox's Latest Holdings Summary section.
Disclaimer: The insider information is derived from SEC filings. The estimated net worth is based on the final shares held after open market or private purchases and sales of common stock with a transaction code of "P" or "S" on Form 4, assuming that John Cox has not made any transactions after 2026-06-16 and currently still holds the listed stock(s). Please note that this estimate may not reflect the actual net worth.
Transaction Summary of John Cox
John Cox Insider Ownership Reports
Based on ownership reports from SEC filings, as the reporting owner, John Cox owns 5 companies in total, including Repligen Corp (RGEN) , Bioverativ Inc (BIVV) , and Biogen Inc (BIIB) among others .
Click here to see the complete history of John Cox’s form 4 insider trades.
Insider Ownership Summary of John Cox
| Ticker | Company | Transaction Date | Type of Owner |
|---|---|---|---|
| RGEN | Repligen Corp | 2020-03-24 | director |
| BIVV | Bioverativ Inc | 2018-03-08 | director & Chief Executive Officer |
| BIIB | Biogen Inc | 2015-03-25 | EVP Pharmaceutical Oper & Tech |
 | | 2020-12-03 | director |
| | 2026-06-16 | director & See Remarks |
John Cox Latest Holdings Summary
John Cox currently owns a total of 3 stocks. Among these stocks, John Cox owns 440,151 shares of Dyne Therapeutics Inc (DYN) as of June 16, 2026, with a value of $12 Million and a weighting of 68.07%. John Cox owns 25,567 shares of Biogen Inc (BIIB) as of March 25, 2015, with a value of $5 Million and a weighting of 31.05%. John Cox also owns 923 shares of Repligen Corp (RGEN) as of March 24, 2020, with a value of $150,463 and a weighting of 0.88%.
Latest Holdings of John Cox
| Ticker | Company | Latest Transaction Date | Shares Owned | Current Price ($) | Current Value ($) |
|---|---|---|---|---|---|
| DYN | Dyne Therapeutics Inc | 2026-06-16 | 440,151 | 26.32 | 11,584,774 |
| BIIB | Biogen Inc | 2015-03-25 | 25,567 | 206.66 | 5,283,548 |
| RGEN | Repligen Corp | 2020-03-24 | 923 | 163.02 | 150,463 |
Holding Weightings of John Cox
John Cox Form 4 Trading Tracker
According to the SEC Form 4 filings, John Cox has made a total of 9 transactions in Dyne Therapeutics Inc (DYN) over the past 5 years, including 2 buys and 7 sells. The most-recent trade in Dyne Therapeutics Inc is the sale of 2,683 shares on June 16, 2026, which brought John Cox around $49,179.
According to the SEC Form 4 filings, John Cox has made a total of 0 transactions in Biogen Inc (BIIB) over the past 5 years. The most-recent trade in Biogen Inc is the sale of 12,010 shares on March 25, 2015, which brought John Cox around $5 Million.
According to the SEC Form 4 filings, John Cox has made a total of 0 transactions in Repligen Corp (RGEN) over the past 5 years. The most-recent trade in Repligen Corp is the sale of 1,858 shares on March 24, 2020, which brought John Cox around $179,706.
Insider Trading History of John Cox
* The information on this page (including Insider Trading Shares, Share Changes, Cost, etc.) is sourced exclusively from Form 4 filings and does not incorporate any data from 13F or 13D/G filings. As a result, it may differ from the values shown on the Guru page.
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John Cox Trading Performance
GuruFocus tracks the stock performance after each of John Cox's buying transactions within different timeframes. To be detailed, the average return of stocks after 3 months bought by John Cox is 30.3%. GuruFocus also compares John Cox's trading performance to market benchmark return within the same time period. The performance of stocks bought by John Cox within 3 months outperforms 1 times out of 2 transactions in total compared to the return of S&P 500 within the same period.
You can select different timeframes to see how John Cox's insider trading performs compared to the benchmark.
Performance of John Cox
Average Return
Outperforming Transactions
| 1 Month | 3 Months | 6 Months | 1 Year | 2 Years | 3 Years | |
|---|---|---|---|---|---|---|
| Return(%) | 18.4 | | | | | |
| Relative Return to S&P 500(%) | 14.71 | | | | | |
John Cox Ownership Network
Ownership Network List of John Cox
Ownership Network Relation of John Cox
John Cox Owned Company Details
What does Repligen Corp do?
Who are the key executives at Repligen Corp?
John Cox is the director of Repligen Corp. Other key executives at Repligen Corp include CFO Jason K Garland , President and CCO Olivier Loeillot , and CHIEF PRODUCT OFFICER Brian Robb Douglass .
Repligen Corp (RGEN) Insider Trades Summary
Over the past 18 months, John Cox made no insider transaction in Repligen Corp (RGEN). Other recent insider transactions involving Repligen Corp (RGEN) include a net sale of 127,314 shares made by Anthony Hunt , a net sale of 10,873 shares made by Olivier Loeillot , and a net sale of 1,263 shares made by Jason K Garland .
In summary, during the past 3 months, insiders sold 1,263 shares of Repligen Corp (RGEN) in total and bought 0 shares, with a net sale of 1,263 shares. During the past 18 months, 141,916 shares of Repligen Corp (RGEN) were sold and 2,050 shares were bought by its insiders, resulting in a net sale of 139,866 shares.
Repligen Corp (RGEN)'s detailed insider trading history can be found in Insider Trading Tracker table.
Repligen Corp Insider Transactions
John Cox Mailing Address
Above is the net worth, insider trading, and ownership report for John Cox. Based on the public information released on the U.S. Securities and Exchange Commission (SEC) website, John Cox's mailing address is: Waltham Ma 02451.
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