MIAX SEC Filing News — Miami International Holdings, Inc.

Latest SEC filings for Miami International Holdings, Inc. (MIAX) explained in plain English. Covers insider buying and selling (Form 4), proposed insider sales (Form 144), material company events (8-K), and quarterly & annual reports (10-Q / 10-K). StrongBuyAnalytics provides navigation and brief excerpts or summaries; original filings remain at the SEC/source links and were authored by their filers, not StrongBuyAnalytics. Filing dates shown are source dates. Coverage and detection can be delayed or incomplete because of SEC availability, amendments, parsing, caching, or outages. Latest source filing date shown: 2026-10-06.

Miami International Holdings, Inc., through its subsidiaries, builds and operates various financial marketplaces in the United States. It operates through Options, Equities, and International segments. The company's markets include options through MIAX Options, MIAX Pearl, MIAX Emerald, and MIAX Sapphire; U.S. equities through MIAX Pearl Equities; U.S. futures and options on futures through MIAX Futures; and international listings through BSX and TISE. It also trades Hard Red Spring Wheat future…
Sector: Financial Services Industry: Capital Markets Market Cap: $3.1B
20
Total Filings
0
Bullish Classifications
13
Bearish Classifications
14
Insider Transactions
0
Material Events (8-K)
1
Periodic Reports
Rule-based classifications for MIAX currently lean bearish. Of the 20 filing records displayed, 13 carry bearish classifications (such as insider sales or negative 8-K disclosures) versus 0 bullish. This does not necessarily signal fundamental deterioration — insiders sell for many reasons — but it is worth monitoring alongside the company's core financial metrics.
MIAX Filing Activity Snapshot 2026-08-06 — 2026-10-06
Insider Transactions (Form 4)
0 buys vs 11 sells
Net insider selling in this period — insiders sell for many reasons beyond conviction.
Largest Form 144 Filing
$6.27M
GALLAGHER INVESTMENTS LLC · 2026-08-19
149,700 shares · Form 144
Form 144 Notices
5
Proposed insider sales filed — Form 144 is a notice of intent, not a confirmed transaction. Actual sales are confirmed via Form 4.
Insider Transactions 14 · Forms 3, 4 and 5

A Form 4 is filed within two business days of a company insider — an officer, a director, or a holder of more than ten percent of the stock — changing their position in the shares. All 14 filings in this group are Form 4s for Miami International Holdings, Inc.

The difficulty with reading these filings as a group is that a single form type covers transactions that mean entirely different things. An executive spending their own money to buy stock and an executive having shares withheld to pay tax on a vesting grant both appear as a Form 4. Every filing below is therefore tagged with the nature of the underlying transaction, taken from the transaction code reported on the form itself.

Across the 14 insider filings shown, the breakdown is 11 open-market sale, 2 tax withholding and 1 option exercise. 11 of them involved a discretionary open-market trade; the rest are compensation and administrative mechanics.

What each transaction type means

Open-market sale ×11
The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.
Tax withholding ×2
Shares were withheld by the company to settle tax due when equity vested. This is an automatic administrative step and not a decision to sell.
Option exercise ×1
The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.
Form 4 Open-market sale Insider Selling 2026-10-06

MIAX insider Schafer Douglas M. JR (EVP and CIO) sold 40,000 shares (~$1.33M)

Schafer Douglas M. JR, listed as EVP and CIO at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 40,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 40,000 $12.00 $480.0K
S Open-market sale 40,000 $33.34 $1.33M
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 40,000 — —
Filing: Form 4 (Insider Transaction) Insider: Schafer Douglas M. JR (EVP and CIO) Shares: 40,000 Est. Value: $1.33M
View on SEC EDGAR → Open Filing Document →
Form 4 Option exercise Tax / Compensation Filing 2026-09-29

MIAX insider Form 4 filed for equity award, exercise, or tax withholding

Jayabalan Harish (EVP, CISO and CRO) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

The insider converted options into shares. The exercise price was fixed when the options were granted, so the timing usually tracks an expiry schedule.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 8,333 $12.00 $100.0K
M Option exercise derivative · Incentive Stock Option (Right to Buy) 8,333 — —
Filing: Form 4 (Insider Transaction) Insider: Jayabalan Harish (EVP, CISO and CRO) Shares: 8,333
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-17

MIAX insider Brown Shelly (EVP, Chief Strategy Officer) sold 21,217 shares (~$819.2K)

Brown Shelly, listed as EVP, Chief Strategy Officer at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 21,217 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 21,217 $38.61 $819.2K
Filing: Form 4 (Insider Transaction) Insider: Brown Shelly (EVP, Chief Strategy Officer) Shares: 21,217 Est. Value: $819.2K
View on SEC EDGAR → Open Filing Document →
Form 4 Tax withholding Tax / Compensation Filing 2026-09-11

MIAX insider Form 4 filed for equity award, exercise, or tax withholding

Brown Shelly (EVP, Chief Strategy Officer) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were withheld by the company to settle tax due when equity vested. This is an automatic administrative step and not a decision to sell.

Transactions reported on this filing
Code Nature Shares Price Value
F Tax withholding on vested shares 16,283 $42.54 $692.7K
Filing: Form 4 (Insider Transaction) Insider: Brown Shelly (EVP, Chief Strategy Officer) Shares: 16,283
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-04

MIAX insider Gallagher Thomas P. (Director, Chairman & CEO) sold 47,000 shares (~$1.99M)

Gallagher Thomas P., listed as Director, Chairman & CEO at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 47,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 47,000 $12.00 $564.0K
S Open-market sale 47,000 $42.43 $1.99M
M Option exercise 16,666 $12.00 $200.0K
M Option exercise 8,333 $12.00 $100.0K
M Option exercise 13,140 $15.22 $200.0K
M Option exercise 4,464 $22.40 $100.0K
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 47,000 — —
M Option exercise derivative · Incentive Stock Option (Right to Buy) 16,666 — —
M Option exercise derivative · Incentive Stock Option (Right to Buy) 8,333 — —
M Option exercise derivative · Incentive Stock Option (Right to Buy) 13,140 — —
M Option exercise derivative · Incentive Stock Option (Right to Buy) 4,464 — —
Filing: Form 4 (Insider Transaction) Insider: Gallagher Thomas P. (Director, Chairman & CEO) Shares: 47,000 Est. Value: $1.99M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-04

MIAX insider Comly Barbara J. (EVP, GC & Corporate Secretary) sold 44,445 shares (~$1.80M)

Comly Barbara J., listed as EVP, GC & Corporate Secretary at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 44,445 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 44,445 $12.00 $533.3K
S Open-market sale 44,445 $40.49 $1.80M
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 44,445 — —
Filing: Form 4 (Insider Transaction) Insider: Comly Barbara J. (EVP, GC & Corporate Secretary) Shares: 44,445 Est. Value: $1.80M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-04

MIAX insider Deitzel Edward (EVP, CRO, CCO MIAX Exchanges) sold 11,000 shares (~$464.3K)

Deitzel Edward, listed as EVP, CRO, CCO MIAX Exchanges at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 11,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 11,000 $12.00 $132.0K
S Open-market sale 11,000 $42.21 $464.3K
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 11,000 — —
Filing: Form 4 (Insider Transaction) Insider: Deitzel Edward (EVP, CRO, CCO MIAX Exchanges) Shares: 11,000 Est. Value: $464.3K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-04

MIAX insider Schafer Douglas M. JR (EVP and CIO) sold 48,000 shares (~$1.94M)

Schafer Douglas M. JR, listed as EVP and CIO at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 48,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 43,334 $12.00 $520.0K
M Option exercise 4,666 $12.00 $56.0K
S Open-market sale 48,000 $40.48 $1.94M
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 43,334 — —
M Option exercise derivative · Nonqualified Stock Option (Right to Buy) 4,666 — —
Filing: Form 4 (Insider Transaction) Insider: Schafer Douglas M. JR (EVP and CIO) Shares: 48,000 Est. Value: $1.94M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-09-04

MIAX insider Teekell Judson Gray (Director) sold 8,545 shares (~$353.2K)

Teekell Judson Gray, listed as Director at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 8,545 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 5,545 $41.58 $230.6K
S Open-market sale 3,000 $40.89 $122.7K
Filing: Form 4 (Insider Transaction) Insider: Teekell Judson Gray (Director) Shares: 8,545 Est. Value: $353.2K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-20

MIAX insider Gallagher Thomas P. (Director, Chairman & CEO) sold 149,700 shares (~$6.16M)

Gallagher Thomas P., listed as Director, Chairman & CEO at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 149,700 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
F Tax withholding on vested shares 150,300 $42.41 $6.37M
S Open-market sale 149,700 $41.13 $6.16M
Filing: Form 4 (Insider Transaction) Insider: Gallagher Thomas P. (Director, Chairman & CEO) Shares: 149,700 Est. Value: $6.16M
View on SEC EDGAR → Open Filing Document →
Form 4 Tax withholding Tax / Compensation Filing 2026-08-20

MIAX insider Form 4 filed for equity award, exercise, or tax withholding

Comly Barbara J. (EVP, GC & Corporate Secretary) filed a Form 4 covering compensation-related activity such as stock awards, option exercises, conversions, or tax withholding. These filings are usually neutral.

Shares were withheld by the company to settle tax due when equity vested. This is an automatic administrative step and not a decision to sell.

Transactions reported on this filing
Code Nature Shares Price Value
F Tax withholding on vested shares 43,420 $42.41 $1.84M
Filing: Form 4 (Insider Transaction) Insider: Comly Barbara J. (EVP, GC & Corporate Secretary) Shares: 43,420
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-19

MIAX insider Schwarzkopf Cynthia (Director) sold 5,000 shares (~$214.2K)

Schwarzkopf Cynthia, listed as Director at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 5,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 5,000 $12.00 $60.0K
S Open-market sale 5,000 $42.85 $214.2K
M Option exercise derivative · Stock Option (Right to Buy) 5,000 — —
Filing: Form 4 (Insider Transaction) Insider: Schwarzkopf Cynthia (Director) Shares: 5,000 Est. Value: $214.2K
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-19

MIAX insider Emmons Lance (EVP and CFO) sold 35,000 shares (~$1.50M)

Emmons Lance, listed as EVP and CFO at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 35,000 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
S Open-market sale 35,000 $42.83 $1.50M
Filing: Form 4 (Insider Transaction) Insider: Emmons Lance (EVP and CFO) Shares: 35,000 Est. Value: $1.50M
View on SEC EDGAR → Open Filing Document →
Form 4 Open-market sale Insider Selling 2026-08-06

MIAX insider Eckert Kurt M. (Director) sold 1,063 shares (~$48.7K)

Eckert Kurt M., listed as Director at MIAMI INTERNATIONAL HOLDINGS, INC., reported an open-market sale of 1,063 MIAX shares in a Form 4 filing. This is a confirmed insider sale, not just a proposed sale notice.

The insider sold shares on the open market. Sales may be discretionary or executed automatically under a pre-arranged Rule 10b5-1 trading plan, and a Form 4 does not always make clear which applies.

Transactions reported on this filing
Code Nature Shares Price Value
M Option exercise 1,063 $12.00 $12.8K
S Open-market sale 1,063 $45.80 $48.7K
M Option exercise derivative · Stock Option (Right to Buy) 1,063 — —
Filing: Form 4 (Insider Transaction) Insider: Eckert Kurt M. (Director) Shares: 1,063 Est. Value: $48.7K
View on SEC EDGAR → Open Filing Document →
Proposed Insider Sales 5 · Form 144

A Form 144 is a notice of intent to sell restricted or control securities. It is not a record that anything was sold. Miami International Holdings, Inc. has 5 such notices in this period.

The distinction matters because a Form 144 is frequently reported as though it were a completed insider sale. The filer may sell all of the shares covered, some of them, or none at all, and there is no obligation to update the notice either way. A sale that is actually executed by an officer or director shows up separately on a Form 4, which is the filing to check before treating a proposed sale as a real one.

Form 144 Proposed Insider Sale 2026-10-02

MIAX Form 144 filed for proposed insider sale by DOUGLAS M. SCHAFER JR. (120,000 shares) ~$4.05M

DOUGLAS M. SCHAFER JR. filed a Form 144 with the SEC indicating intent to sell MIAX (MIAMI INTERNATIONAL HOLDINGS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: DOUGLAS M. SCHAFER JR. Shares: 120,000 Est. Value: $4.05M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-09-16

MIAX Form 144 filed for proposed insider sale by SHELLY BROWN (21,217 shares) ~$838.3K

SHELLY BROWN filed a Form 144 with the SEC indicating intent to sell MIAX (MIAMI INTERNATIONAL HOLDINGS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: SHELLY BROWN Shares: 21,217 Est. Value: $838.3K
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-09-03

MIAX Form 144 filed for proposed insider sale by GALLAGHER INVESTMENTS LLC (141,000 shares) ~$5.73M

GALLAGHER INVESTMENTS LLC filed a Form 144 with the SEC indicating intent to sell MIAX (MIAMI INTERNATIONAL HOLDINGS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: GALLAGHER INVESTMENTS LLC Shares: 141,000 Est. Value: $5.73M
View on SEC EDGAR → Open Filing Document →
Form 144 Large Proposed Insider Sale 2026-08-19

MIAX Form 144 filed for proposed insider sale by GALLAGHER INVESTMENTS LLC (149,700 shares) ~$6.27M

GALLAGHER INVESTMENTS LLC filed a Form 144 with the SEC indicating intent to sell MIAX (MIAMI INTERNATIONAL HOLDINGS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4. The proposed dollar value is large enough to merit attention.

Filing: Form 144 (Proposed Sale Notice) Insider: GALLAGHER INVESTMENTS LLC Shares: 149,700 Est. Value: $6.27M
View on SEC EDGAR → Open Filing Document →
Form 144 Proposed Insider Sale 2026-08-17

MIAX Form 144 filed for proposed insider sale by Lance Emmons (35,000 shares) ~$1.52M

Lance Emmons filed a Form 144 with the SEC indicating intent to sell MIAX (MIAMI INTERNATIONAL HOLDINGS, INC.) shares. Form 144 reflects a proposed sale, not a completed transaction. The actual execution, if any, would typically appear later in a Form 4.

Filing: Form 144 (Proposed Sale Notice) Insider: Lance Emmons Shares: 35,000 Est. Value: $1.52M
View on SEC EDGAR → Open Filing Document →
Periodic Reports 1 · Forms 10-K and 10-Q

The periodic reports are where the audited and reviewed financial statements live. This period contains 1 quarterly report (10-Q) for Miami International Holdings, Inc.

The two are not equivalent in weight. A 10-K is audited by an external firm and includes the full risk factor disclosure, business description and management discussion; a 10-Q is unaudited, reviewed rather than examined, and much shorter. When a figure in a quarterly report is later revised, the annual report is usually where the correction appears.

An amended report — 10-K/A or 10-Q/A — restates or corrects something in the original filing, and is worth reading against the version it replaces.

Form 10-Q Quarterly Report 2026-08-07

MIAX filed Quarterly Report (10-Q)

MIAMI INTERNATIONAL HOLDINGS, INC. filed its quarterly report with the SEC. This report includes unaudited financial statements and management discussion for the quarter.

Filing: 10-Q (Quarterly Report)
View on SEC EDGAR → Open Filing Document →

How we classify Miami International Holdings, Inc.'s filings

Straight from EDGAR

Each displayed record links to an original source document. StrongBuyAnalytics provides navigation and brief excerpts or summaries, not the filing itself. Parsing may omit context or contain errors, so read the original document in full.

Transaction codes, not guesswork

The nature shown on each insider filing comes from the transaction code the filer entered on the form itself — P for an open-market purchase, A for a compensation award, F for shares withheld to pay tax, M for an option exercise. Where one filing contains several codes, the transaction table lists them line by line.

Why the distinction matters

Insider activity is routinely summarised as buying or selling, which flattens together decisions that mean very different things. Shares withheld for tax on a vesting grant are an automatic administrative step; shares bought on the open market are someone committing their own money at the current price.

What this page does not tell you

A filing records what happened, not why. Form 4 does not always disclose whether a sale was executed under a pre-arranged Rule 10b5-1 plan, and no single filing is a basis for a decision on MIAX. Read these alongside the fundamentals rather than in isolation.

Frequently Asked Questions — MIAX SEC Filings

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Publisher, sources & limitations — September 15, 2026. StrongBuyAnalytics provides navigation and brief excerpts or summaries for educational use. Original filings remain at SEC EDGAR or other displayed source links; StrongBuyAnalytics does not author them. Filing dates are source dates, not publication dates for this page. Coverage can be delayed, incomplete, amended, or unavailable because of SEC/source availability, parsing, caching, or outages. Verify every material statement in the original filing.
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