Matthew Tappin
Insider
First SEC filing: July 24, 2023 · Latest: July 24, 2023
Insider at
Insider transactions
0 buys (P)
7 sells (S)
Net: $-198,017
Price change vs current quote, split-adjusted for corporate actions since the filing — not benchmarked, not annualized, not size-weighted
| Date | Ticker | Code | Shares | Price | Value | Owned after | Δ own | A/D | vs now |
|---|---|---|---|---|---|---|---|---|---|
| July 2, 2026 | STEM | S | 996 | $7.85 | $7,819 | 9,577 Direct | -9.42% | Disposed | -45.9% (price as of 2026-10-05) |
| June 30, 2026 | STEM | M | 5,000 | · | · | 5,000 Direct | -50.00% | Disposed | (price as of 2026-10-05) |
| June 30, 2026 | STEM | M | 2,750 | · | · | 2,750 Direct | -50.00% | Disposed | (price as of 2026-10-05) |
| June 30, 2026 | STEM | M | 2,750 | $7.81 | $21,478 | 10,573 Direct | +35.15% | Acquired | -45.6% (price as of 2026-10-05) |
| June 30, 2026 | STEM | M | 5,000 | $7.81 | $39,050 | 7,823 Direct | +177.12% | Acquired | -45.6% (price as of 2026-10-05) |
| March 11, 2026 | STEM | S 10b5-1 | 402 | $10.83 | $4,354 | 2,823 Direct | -12.47% | Disposed | -60.8% (price as of 2026-10-05) |
| March 10, 2026 | STEM | S | 655 | $11.12 | $7,284 | 3,225 Direct | -16.88% | Disposed | -61.8% (price as of 2026-10-05) |
| March 7, 2026 | STEM | M | 1,458 | · | · | 3,880 Direct | +60.20% | Acquired | (price as of 2026-10-05) |
| March 7, 2026 | STEM | M | 1,458 | · | · | 1,459 Direct | -49.98% | Disposed | (price as of 2026-10-05) |
| March 4, 2026 | STEM | S | 185 | $10.00 | $1,850 | 2,422 Direct | -7.10% | Disposed | -57.5% (price as of 2026-10-05) |
| March 3, 2026 | STEM | S | 300 | $9.67 | $2,901 | 2,607 Direct | -10.32% | Disposed | -56.0% (price as of 2026-10-05) |
| March 1, 2026 | STEM | M | 670 | · | · | 2,907 Direct | +29.95% | Acquired | (price as of 2026-10-05) |
| March 1, 2026 | STEM | M | 670 | · | · | 0 Direct | -100.00% | Disposed | (price as of 2026-10-05) |
| Feb. 26, 2026 | STEM | A | 25,800 | · | · | 25,800 Direct | · | Acquired | (price as of 2026-10-05) |
| Feb. 26, 2026 | STEM | A | 17,200 | · | · | 17,200 Direct | · | Acquired | (price as of 2026-10-05) |
| Feb. 20, 2026 | STEM | S | 366 | $11.40 | $4,172 | 2,237 Direct | -14.06% | Disposed | -62.7% (price as of 2026-10-05) |
| Feb. 19, 2026 | STEM | F | 522 | $11.30 | $5,899 | 2,603 Direct | -16.70% | Disposed | -62.4% (price as of 2026-10-05) |
| Feb. 15, 2026 | STEM | M | 1,253 | · | · | 3,125 Direct | +66.93% | Acquired | (price as of 2026-10-05) |
| Feb. 15, 2026 | STEM | M | 1,253 | · | · | 0 Direct | -100.00% | Disposed | (price as of 2026-10-05) |
| Nov. 11, 2025 | STEM | S | 9,584 | $17.70 | $169,637 | 1,872 Direct | -83.66% | Disposed | -76.0% (price as of 2026-10-05) |
| Nov. 10, 2025 | STEM | F | 5,416 | $18.27 | $98,950 | 11,456 Direct | -32.10% | Disposed | -76.7% (price as of 2026-10-05) |
| Nov. 7, 2025 | STEM | M | 15,000 | · | · | 16,872 Direct | +801.28% | Acquired | (price as of 2026-10-05) |
| Nov. 7, 2025 | STEM | M | 15,000 | · | · | 0 Direct | -100.00% | Disposed | (price as of 2026-10-05) |
| July 28, 2025 | STEM | A | 10,000 | · | · | 10,000 Direct | · | Acquired | (price as of 2026-10-05) |
| July 28, 2025 | STEM | A | 10,000 | · | · | 10,000 Direct | · | Acquired | (price as of 2026-10-05) |
| June 30, 2025 | STEM | A | 5,500 | · | · | 5,500 Direct | · | Acquired | (price as of 2026-10-05) |
| June 30, 2025 | STEM | A | 5,500 | · | · | 5,500 Direct | · | Acquired | (price as of 2026-10-05) |
| June 30, 2025 | STEM | A | 11,000 | · | · | 11,000 Direct | · | Acquired | (price as of 2026-10-05) |
| June 16, 2025 | STEM | S 10b5-1 | 20,823 | $0.45 | $9,370 | 37,458 Direct | -35.73% | Disposed | -52.8% (price as of 2026-10-05) |
| May 30, 2025 | STEM | S | 1,164 | $0.45 | $524 | 58,281 Direct | -1.96% | Disposed | -52.8% (price as of 2026-10-05) |
| May 29, 2025 | STEM | M | 2,775 | · | · | 396,784 Direct | -0.69% | Disposed | (price as of 2026-10-05) |
| May 29, 2025 | STEM | M | 2,775 | · | · | 59,445 Direct | +4.90% | Acquired | (price as of 2026-10-05) |
| March 12, 2025 | STEM | S | 13,070 | $0.40 | $5,228 | 56,670 Direct | -18.74% | Disposed | -46.9% (price as of 2026-10-05) |
| March 11, 2025 | STEM | M | 29,167 | · | · | 399,559 Direct | -6.80% | Disposed | (price as of 2026-10-05) |
| March 11, 2025 | STEM | M | 29,167 | · | · | 69,740 Direct | +71.89% | Acquired | (price as of 2026-10-05) |
| March 7, 2025 | STEM | S | 5,645 | $0.42 | $2,371 | 40,573 Direct | -12.21% | Disposed | -49.4% (price as of 2026-10-05) |
| March 6, 2025 | STEM | M | 13,397 | · | · | 428,726 Direct | -3.03% | Disposed | (price as of 2026-10-05) |
| March 6, 2025 | STEM | M | 13,397 | · | · | 46,218 Direct | +40.82% | Acquired | (price as of 2026-10-05) |
| Feb. 20, 2025 | STEM | S | 8,130 | $0.63 | $5,122 | 32,821 Direct | -19.85% | Disposed | -66.3% (price as of 2026-10-05) |
| Feb. 19, 2025 | STEM | M | 24,316 | · | · | 442,123 Direct | -5.21% | Disposed | (price as of 2026-10-05) |
| Feb. 19, 2025 | STEM | M | 24,316 | · | · | 40,951 Direct | +146.17% | Acquired | (price as of 2026-10-05) |
| Nov. 1, 2024 | STEM | A | 300,000 | · | · | 466,439 Direct | +180.25% | Acquired | (price as of 2026-10-05) |
| May 28, 2024 | STEM | S 10b5-1 | 1,388 | $1.32 | $1,832 | 16,635 Direct | -7.70% | Disposed | -83.9% (price as of 2026-10-05) |
| May 28, 2024 | STEM | A | 87,500 | · | · | 166,439 Direct | +110.85% | Acquired | (price as of 2026-10-05) |
| May 24, 2024 | STEM | M | 2,775 | · | · | 18,023 Direct | +18.20% | Acquired | (price as of 2026-10-05) |
| May 24, 2024 | STEM | M | 2,775 | · | · | 78,939 Direct | -3.40% | Disposed | (price as of 2026-10-05) |
| March 19, 2024 | STEM | S | 26,640 | $1.82 | $48,485 | 15,248 Direct | -63.60% | Disposed | -88.3% (price as of 2026-10-05) |
| March 8, 2024 | STEM | S 10b5-1 | 24,899 | $2.19 | $54,529 | 41,888 Direct | -37.28% | Disposed | -90.3% (price as of 2026-10-05) |
| March 5, 2024 | STEM | S 10b5-1 | 3,837 | $2.41 | $9,247 | 66,787 Direct | -5.43% | Disposed | -91.2% (price as of 2026-10-05) |
| March 4, 2024 | STEM | S | 5,724 | $2.48 | $14,196 | 70,624 Direct | -7.50% | Disposed | -91.4% (price as of 2026-10-05) |
| March 1, 2024 | STEM | M | 13,398 | · | · | 24,809 Direct | +117.41% | Acquired | (price as of 2026-10-05) |
| March 1, 2024 | STEM | A | 51,539 | · | · | 76,348 Direct | +207.74% | Acquired | (price as of 2026-10-05) |
| March 1, 2024 | STEM | M | 13,398 | · | · | 81,714 Direct | -14.09% | Disposed | (price as of 2026-10-05) |
| Feb. 20, 2024 | STEM | S 10b5-1 | 6,857 | $3.05 | $20,914 | 11,411 Direct | -37.54% | Disposed | -93.0% (price as of 2026-10-05) |
| Feb. 16, 2024 | STEM | S | 10,602 | $3.17 | $33,608 | 18,268 Direct | -36.72% | Disposed | -93.3% (price as of 2026-10-05) |
| Feb. 15, 2024 | STEM | M | 24,315 | · | · | 28,870 Direct | +533.81% | Acquired | (price as of 2026-10-05) |
| Feb. 15, 2024 | STEM | M | 24,315 | · | · | 95,112 Direct | -20.36% | Disposed | (price as of 2026-10-05) |
| Feb. 15, 2024 | STEM | A | 45,024 | · | · | 45,024 Direct | · | Acquired | (price as of 2026-10-05) |
| Feb. 14, 2024 | STEM | S 10b5-1 | 4,556 | $3.15 | $14,351 | 4,555 Direct | -50.01% | Disposed | -93.3% (price as of 2026-10-05) |
| Jan. 3, 2024 | STEM | S 10b5-1 | 5,207 | $3.56 | $18,537 | 9,111 Direct | -36.37% | Disposed | -94.0% (price as of 2026-10-05) |
| Dec. 31, 2023 | STEM | M | 14,318 | · | · | 14,318 Direct | · | Acquired | (price as of 2026-10-05) |
| Dec. 31, 2023 | STEM | M | 14,318 | · | · | 119,427 Direct | -10.71% | Disposed | (price as of 2026-10-05) |
P = Open-market purchase · S = Sale · A = Grant/award · M = Option exercise · G = Gift · F = Tax withholding
Insider transactions are not a recommendation; sales are often driven by liquidity or tax reasons.
Derivative holdings (Form 4 Table II) Options, RSUs and convertible securities reported on Form 4 Table II.
| Date | Ticker | Security | Underlying | Exercise price | Expiration | Shares | A/D |
|---|---|---|---|---|---|---|---|
| June 30, 2026 | STEM | Performance Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 5,000 | Disposed |
| June 30, 2026 | STEM | Performance Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 2,750 | Disposed |
| March 7, 2026 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 1,458 | Disposed |
| March 1, 2026 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 670 | Disposed |
| Feb. 26, 2026 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 25,800 | Acquired |
| Feb. 26, 2026 | STEM | Performance Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 17,200 | Acquired |
| Feb. 15, 2026 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 1,253 | Disposed |
| Nov. 7, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 15,000 | Disposed |
| July 28, 2025 | STEM | Performance Stock Unit | Common Stock, Par Value 0.0001 Per Share | · | · | 10,000 | Acquired |
| July 28, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value 0.0001 Per Share | · | · | 10,000 | Acquired |
| June 30, 2025 | STEM | Stock Options | Common Stock, Par Value 0.0001 Per Share | $6.23 | June 30, 2035 | 5,500 | Acquired |
| June 30, 2025 | STEM | Performance Stock Unit | Common Stock, Par Value 0.0001 Per Share | · | · | 5,500 | Acquired |
| June 30, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value 0.0001 Per Share | · | · | 11,000 | Acquired |
| May 29, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 2,775 | Disposed |
| March 11, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 29,167 | Disposed |
| March 6, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 13,397 | Disposed |
| Feb. 19, 2025 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 24,316 | Disposed |
| Nov. 1, 2024 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 300,000 | Acquired |
| May 28, 2024 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 87,500 | Acquired |
| May 24, 2024 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 2,775 | Disposed |
| March 1, 2024 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 13,398 | Disposed |
| Feb. 15, 2024 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | $0.00 | · | 24,315 | Disposed |
| Feb. 15, 2024 | STEM | Stock Option (Right to Buy) | Common Stock, Par Value $0.0001 Per Share | $3.37 | Feb. 15, 2034 | 45,024 | Acquired |
| Dec. 31, 2023 | STEM | Restricted Stock Unit | Common Stock, Par Value $0.0001 Per Share | · | · | 14,318 | Disposed |
Exercise/conversion price is blank when not applicable (e.g. RSUs).
Initial ownership (Form 3) 4 holdings
Securities held when first becoming an insider, per SEC Form 3.