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 3mo) | 1 |
| Riot | COO | 2024-07 → present (2y 2mo) | 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 | 1,634,315 | $0 | 269,686 | $4.48M | ↓ Divested $4.48M | 13 | $35.63M | $5.88M |
| 2026 | 591,948 | $0 | 225,808 | $3.99M | ↓ Divested $3.99M | 6 | $12.90M | $4.92M |
| 2025 | 665,483 | $0 | 40,690 | $458.6K | ↓ Divested $458.6K | 4 | $14.51M | $887.0K |
| 2024 | 376,884 | $0 | 3,188 | $31.7K | ↓ Divested $31.7K | 3 | $8.22M | $69.5K |
| 2024-Q3 | 376,884 | $0 | 3,188 | $31.7K | ↓ Divested $31.7K | 3 | $8.22M | $69.5K |
| 2025-Q3 | 665,483 | $0 | 40,690 | $458.6K | ↓ Divested $458.6K | 4 | $14.51M | $887.0K |
| 2026-Q1 | 591,948 | $0 | 29,482 | $373.5K | ↓ Divested $373.5K | 3 | $12.90M | $642.7K |
| 2026-Q3 | - | $0 | 196,326 | $3.62M | ↓ Divested $3.62M | 3 | $0 | $4.28M |
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 2026-09-04); 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 | - | $462.1K |
| 2026-07-31 | Riot | Tax withholding on vesting | 153,162 | $3,089,278 | $3.34M |
| 2026-07-01 | Riot | Tax withholding on vesting | 21,966 | $526,305 | $478.9K |
| 2026-01-01 | Riot | Tax withholding on vesting | 29,482 | $373,537 | $642.7K |
| 2026-01-01 | Riot | Grant / award / vesting | 197,316 | - | $4.30M |
| 2026-01-01 | Riot | Grant / award / vesting | 394,632 | - | $8.60M |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $443.5K |
| 2025-07-01 | Riot | Tax withholding on vesting | 20,345 | $229,288 | $443.5K |
| 2025-07-01 | Riot | Grant / award / vesting | 221,827 | - | $4.84M |
| 2025-07-01 | Riot | Grant / award / vesting | 443,656 | - | $9.67M |
| 2024-07-01 | Riot | Tax withholding on vesting | 3,188 | $31,721 | $69.5K |
| 2024-07-01 | Riot | Grant / award / vesting | 125,628 | - | $2.74M |
| 2024-07-01 | Riot | Grant / award / vesting | 251,256 | - | $5.48M |