David M Demski insider trades: Alphatec Holdings (ATEC) stock buys and sales
Trades on the price chart
Daily close, with an arrow on each day they bought or sold
Companies
Where David reports to the SEC
Open-market buys and sales
23 trades reported on SEC Form 4, newest first
| Date | Stock | Type | Shares | Price | Value | Holding | Reported |
|---|---|---|---|---|---|---|---|
| Oct 30, 2026 | ATEC | ↑ Buy | 60,000 | $6.81 | $409K | Direct | Nov 2, 2026 (3d) |
| Dec 11, 2025 | ATEC | ↓ Sell | 30,000 | $21.20 | $636K | Direct | Dec 12, 2025 (1d) |
| Aug 21, 2024 | ATEC | ↑ Buy | 50,000 | $5.67 | $284K | Direct | Aug 21, 2024 (0d) |
| Aug 2, 2024 | ATEC | ↑ Buy | 40,000 | $6.56 | $262K | Direct | Aug 5, 2024 (3d) |
| Nov 9, 2023 | ATEC | ↑ Buy | 30,000 | $10.50 | $315K | Direct | Nov 13, 2023 (4d) |
| Apr 26, 2021 | GMED | ↓ Sell | 265,522 | $71.54 | $19.0M | Direct | Apr 27, 2021 (1d) |
| Dec 17, 2020 | GMED | ↓ Sell | 217,075 | $64.20 | $13.9M | Direct | Dec 18, 2020 (1d) |
| Aug 6, 2020 | GMED | ↓ Sell | 330,000 | $56.39 | $18.6M | Direct | Aug 10, 2020 (4d) |
| Apr 19, 2018 | GMED | ↓ Sell | 149,109 | $51.00 | $7.6M | Direct | Apr 20, 2018 (1d) |
| Apr 13, 2018 | GMED | ↓ Sell | 50,891 | $51.00 | $2.6M | Direct | Apr 16, 2018 (3d) |
| Feb 26, 2015 | GMED | ↓ Sell | 32,510 | $26.00 | $845K | Direct | Mar 2, 2015 (4d) |
| Mar 6, 2014 | GMED | ↓ Sell | 271,329 | $25.83 | $7.0M | Direct | Mar 10, 2014 (4d) |
| Jan 15, 2014 | GMED | ↓ Sell | 96,813 | $20.51 | $2.0M | Direct | Jan 16, 2014 (1d) |
| Dec 31, 2013 | GMED | ↓ Sell | 3,187 | $20.25 | $65K | Direct | Jan 2, 2014 (2d) |
| Dec 20, 2013 | GMED | ↓ Sell | 50,000 | $19.75 | $988K | Direct | Dec 20, 2013 (0d) |
| Nov 27, 2013 | GMED | ↓ Sell | 37,323 | $19.25 | $718K | Direct | Nov 27, 2013 (0d) |
| Nov 1, 2013 | GMED | ↓ Sell | 112,677 | $18.59 | $2.1M | Direct | Nov 4, 2013 (3d) |
| Aug 22, 2013 | GMED | ↓ Sell | 40,000 | $17.95 | $718K | Direct | Aug 26, 2013 (4d) |
| Aug 22, 2013 | GMED | ↓ Sell | 4,154 | $17.95 | $75K | By wife | Aug 26, 2013 (4d) |
| May 3, 2013 | GMED | ↓ Sell | 40,000 | $16.25 | $650K | Direct | May 7, 2013 (4d) |
| Mar 11, 2013 | GMED | ↓ Sell | 14,225 | $15.00 | $213K | Direct | Mar 13, 2013 (2d) |
| Feb 13, 2013 | GMED | ↓ Sell | 25,775 | $15.00 | $387K | Direct | Feb 15, 2013 (2d) |
| Aug 8, 2012 | GMED | ↓ Sell | 98,957 | $11.16 | $1.1M | Direct | Aug 10, 2012 (2d) |
Each row is one filing's trades in one stock, summed. Shares and prices are as filed, before any later stock split.
Other ATEC insiders
Open-market trades in the last 12 months
About David M Demski's insider trades
David M Demski is an insider at Alphatec Holdings (ATEC). Since Aug 8, 2012, David has reported 4 open-market purchases worth $1.3M and 19 sales worth $79.2M on SEC Form 4. In the last 12 months: 1 buy ($409K) and 1 sale ($636K).
Their filings also include grants and awards (22 filings), option exercises (6 filings), shares returned to the company (2 filings), gifts (1 filing). These aren't open-market trades and aren't counted above.
How to read insider trades
Officers, directors and owners of more than 10% of a company must report trades in its stock on SEC Form 4, usually within two business days. Purchases with their own money are the stronger signal: insiders sell for many reasons (taxes, diversification, a house), but buy for one. See every ATEC insider trade, the latest insider trades across the market, or cluster buys, when several insiders buy the same stock within days.