Howell Stephen Mitchell Jr. is Chief Operating Officer (COO) of Riot Platforms, Inc. The Form 4 filing carries no fuller biographical information beyond his current title and company affiliation.
Biography extracted from Riot Form 4 filed 2026-08-14 View cached copy (2026-08-30)Live source ↗
Roles
Contiguous filings for the same role are collapsed into a single tenure span. Click a row to see the underlying filings.
| Company | Role | Tenure | Filings |
|---|---|---|---|
| Riot | COO (See Remarks) | 2024-06 → present (2y 4mo) | 1 |
| Riot | COO | 2024-07 → present (2y 3mo) | 6 |
Show 6 underlying filings | |||
Insider transactions
Totals for this person
| Bucket | Invested (shares) | Invested (USD) | Divested (shares) | Divested (USD) | Net direction | Txns | Invested @ last price | Divested @ last price |
|---|---|---|---|---|---|---|---|---|
| All time | 3,268,630 | $0 | 539,372 | $8.96M | ↓ Divested $8.96M | 26 | $45.66M | $7.54M |
| 2026 | 1,183,896 | $0 | 451,616 | $7.98M | ↓ Divested $7.98M | 12 | $16.54M | $6.31M |
| 2025 | 1,330,966 | $0 | 81,380 | $917.2K | ↓ Divested $917.2K | 8 | $18.59M | $1.14M |
| 2024 | 753,768 | $0 | 6,376 | $63.4K | ↓ Divested $63.4K | 6 | $10.53M | $89.1K |
| 2024-Q3 | 753,768 | $0 | 6,376 | $63.4K | ↓ Divested $63.4K | 6 | $10.53M | $89.1K |
| 2025-Q3 | 1,330,966 | $0 | 81,380 | $917.2K | ↓ Divested $917.2K | 8 | $18.59M | $1.14M |
| 2026-Q1 | 1,183,896 | $0 | 58,964 | $747.1K | ↓ Divested $747.1K | 6 | $16.54M | $823.7K |
| 2026-Q3 | - | $0 | 392,652 | $7.23M | ↓ Divested $7.23M | 6 | $0 | $5.49M |
Invested = shares acquired (buys, grants, option exercises) — insider adding to the position. Divested = shares reduced (sells, dispositions, tax-withholding) — cash flowing TO the insider. Net direction shows which side wins on dollar terms in each bucket. % of holder's stake not yet computed (pending Form 3/4 holdings ingest). See methodology. The two @ last price columns restate the same share counts at the most recent share price we read (close of 2026-10-19); they are a valuation, not a cash flow, and they move every day the market does.
All transactions
| Date | Company | Kind | Shares | Amount (USD) | Value @ last price |
|---|---|---|---|---|---|
| 2026-08-12 | Riot | Bona fide gift | 21,198 | - | $296.1K |
| 2026-08-12 | Riot | Bona fide gift | 21,198 | - | $296.1K |
| 2026-07-31 | Riot | Tax withholding on vesting | 153,162 | $3,089,278 | $2.14M |
| 2026-07-31 | Riot | Tax withholding on vesting | 153,162 | $3,089,278 | $2.14M |
| 2026-07-01 | Riot | Tax withholding on vesting | 21,966 | $526,305 | $306.9K |
| 2026-07-01 | Riot | Tax withholding on vesting | 21,966 | $526,305 | $306.9K |
| 2026-01-01 | Riot | Tax withholding on vesting | 29,482 | $373,537 | $411.9K |
| 2026-01-01 | Riot | Grant / award / vesting | 394,632 | - | $5.51M |
| 2026-01-01 | Riot | Tax withholding on vesting | 29,482 | $373,537 | $411.9K |
| 2026-01-01 | Riot | Grant / award / vesting | 197,316 | - | $2.76M |
| 2026-01-01 | Riot | Grant / award / vesting | 394,632 | - | $5.51M |
| 2026-01-01 | Riot | Grant / award / vesting | 197,316 | - | $2.76M |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $284.2K |
| 2025-07-01 | Riot | Grant / award / vesting | 221,827 | - | $3.10M |
| 2025-07-01 | Riot | Grant / award / vesting | 221,827 | - | $3.10M |
| 2025-07-01 | Riot | Grant / award / vesting | 443,656 | - | $6.20M |
| 2025-07-01 | Riot | Grant / award / vesting | 443,656 | - | $6.20M |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $284.2K |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $284.2K |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $284.2K |
Show older transactions (6 more)
| Date | Company | Kind | Shares | Amount (USD) | Value @ last price |
|---|---|---|---|---|---|
| 2024-07-01 | Riot | Grant / award / vesting | 125,628 | - | $1.76M |
| 2024-07-01 | Riot | Grant / award / vesting | 251,256 | - | $3.51M |
| 2024-07-01 | Riot | Tax withholding on vesting | 3,188 | $31,721 | $44.5K |
| 2024-07-01 | Riot | Grant / award / vesting | 125,628 | - | $1.76M |
| 2024-07-01 | Riot | Tax withholding on vesting | 3,188 | $31,721 | $44.5K |
| 2024-07-01 | Riot | Grant / award / vesting | 251,256 | - | $3.51M |