D. Mark DeWalch is Director at Black Stone Minerals, L.P. (BSM). They have made 10 open-market trades across 1 company since 2015, most recently 2026-10-02.
CIK 0001638259
Unrated. We grade insiders only on stock they chose to buy on the open market. Grants, option exercises and vesting say nothing about timing, so they don't count — which is why someone can file often and still have no grade. It isn't a bad sign: unrated buys beat every graded tier below A.
10 open-market purchases totalling $4.8M since 2015, never a sale. Across 10 scored buys the stock is up 3.1% at ninety days, and 1.1 points behind the S&P over the same stretch.
10 scored purchases · one row per filing · discretionary only
| Ticker | Shares | Value |
|---|---|---|
| BSM | 434,146 | $6.5M |
Shares reported on the most recent Form 4, priced at the 2026-10-05 close.
Counted per filing, not per execution lot — a purchase filled in several tranches is one decision.
| 7d | 30d | 90d | |
|---|---|---|---|
| Accuracy | 50% | 70% | 80% |
| Avg Move | -1.4% | +0.8% | +3.1% |
| Alpha | -0.6% | -0.0% | -1.1% |
| Scored | 10 | 10 | 10 |
| Ticker | Type | Traded | Filed | Price | Value | 7d Stock | 30d Stock | 90d Stock |
|---|---|---|---|---|---|---|---|---|
| BSM | BUY | 2026-05-29 | 2026-06-02 | $13.55 | $985K | +1.9% | +0.5% | +8.5% |
| BSM | BUY | 2026-05-28 | 2026-05-28 | $13.21 | $497K | +2.9% | +5.0% | +11.1% |
| BSM | BUY | 2024-08-15 | 2024-08-15 | $14.62 | $500K | +0.8% | +2.1% | +3.9% |
| BSM | BUY | 2024-02-26 | 2024-02-27 | $15.47 | $101K | +0.5% | +3.0% | +3.9% |
| BSM | BUY | 2023-11-16 | 2023-11-17 | $17.32 | $1.5M | +0.3% | -6.3% | -12.3% |
| BSM | BUY | 2023-03-06 | 2023-03-07 | $15.85 | $1.0M | -6.3% | +2.4% | +5.2% |
| BSM | BUY | 2019-06-10 | 2019-06-12 | $16.44 | $88K | -4.3% | -3.5% | -7.4% |
| BSM | BUY | 2018-11-16 | 2018-11-19 | $17.06 | $20K | -1.5% | -7.5% | +5.7% |
| BSM | BUY | 2015-07-30 | 2015-08-03 | $14.56 | $218 | -4.3% | +6.2% | +6.2% |
| BSM | BUY | 2015-05-06 | 2015-05-08 | $19.00 | $70K | -4.3% | +6.2% | +6.2% |
Grouped by shared companies and similar filing behaviour. This is a similarity measure, not a ranking or a performance signal.