CSTL's three largest insider shareholders as of August 27, 2026 are Derek J Maetzold (Pres. Chief Exec. Officer, 119.35K shares), Kristen M Oelschlager (Chief Operating Officer, 100.94K shares), Tobin W Juvenal (Chief Commercial Officer, 86.83K shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Derek J Maetzold | Pres. Chief Exec. Officer | 21,479 | 83,792 | 105,271 | 17.9% | 18 Aug, 2026 |
| 2 | Tobin W Juvenal | Chief Commercial Officer | 75,964 | 0 | 75,964 | 12.9% | 19 Aug, 2026 |
| 3 | Kristen M Oelschlager | Chief Operating Officer | 0 | 72,649 | 72,649 | 12.3% | 26 Aug, 2026 |
| 4 | Mara G. Aspinall | Director | 44,139 | 0 | 44,139 | 7.5% | 04 Jun, 2024 |
| 5 | Ellen Goldberg | Director | 40,921 | 0 | 40,921 | 7.0% | 27 May, 2025 |
| 6 | Tiffany Olson | Director | 39,573 | 0 | 39,573 | 6.7% | 27 May, 2025 |
| 7 | Kim Caple | Director | 36,121 | 0 | 36,121 | 6.1% | 27 May, 2025 |
| 8 | Miles Harrison | Director | 35,631 | 0 | 35,631 | 6.1% | 27 May, 2025 |
| 9 | Frank Stokes | Chief Financial Officer | 35,177 | 0 | 35,177 | 6.0% | 18 Aug, 2026 |
| 10 | Rodney Cotton | Director | 32,998 | 0 | 32,998 | 5.6% | 27 May, 2025 |
| 11 | G Bradley Cole | Director | 32,976 | 0 | 32,976 | 5.6% | 27 May, 2026 |
| 12 | Daniel Bradbury | Director | 22,340 | 0 | 22,340 | 3.8% | 27 May, 2025 |
| 13 | Bernhard E. Spiess | Chief Business Officer | 14,696 | 0 | 14,696 | 2.5% | 14 Dec, 2021 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 24 Aug, 2026 | Kristen M Oelschlager | Chief Operating Officer | Disposed S | 12,218 | $33.69 | $411.59K | 85,033 | Indirect |
| 25 Aug, 2026 | Kristen M Oelschlager | Chief Operating Officer | Disposed S | 7,161 | $34.26 | $245.36K | 77,872 | Indirect |
| 25 Aug, 2026 | Kristen M Oelschlager | Chief Operating Officer | Disposed S | 5,223 | $34.64 | $180.92K | 72,649 | Indirect |
| 17 Aug, 2026 | Tobin W Juvenal | Chief Commercial Officer | Disposed S | 1,730 | $29.59 | $51.19K | 75,964 | Direct |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Acquired M | 1,100 | $2.39 | $2.63K | 22,579 | Direct |
| 14 Aug, 2026 | Frank Stokes | Chief Financial Officer | Disposed S | 24,908 | $29.77 | $741.51K | 35,177 | Direct |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 1,100 | $30.02 | $33.02K | 21,479 | Direct |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 2,714 | $30.02 | $81.47K | 20,355 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 2,306 | $30.02 | $69.23K | 17,301 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 278 | $30.02 | $8.35K | 11,534 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 278 | $30.02 | $8.35K | 11,534 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 278 | $30.02 | $8.35K | 11,534 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 278 | $30.02 | $8.35K | 11,534 | Indirect |
| 14 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed M | 1,100 | $0.00 | $0 | 37,757 | Direct |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Acquired M | 20,356 | $2.39 | $48.65K | 41,835 | Direct |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 8,421 | $30.79 | $259.27K | 33,414 | Direct |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 3,374 | $30.79 | $103.88K | 28,407 | Indirect |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 2,866 | $30.79 | $88.24K | 24,143 | Indirect |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 11,935 | $31.34 | $374.00K | 21,479 | Direct |
| 04 Aug, 2026 | Derek J Maetzold | Pres. Chief Exec. Officer | Disposed S | 4,782 | $31.34 | $149.85K | 23,625 | Indirect |