| Period | Weighting | Quarter | ||||||
|---|---|---|---|---|---|---|---|---|
| Company | Longest | Shortest | Min. | Avg. | Max. | First | Latest | ↓ Count |
| GROUP ONE TRADING, L.P. | 8 | 8 | 0.00% | 0.01% | 0.02% | Q3 2013 | Q2 2015 | 8 |
| SIMPLEX TRADING, LLC | 1 | 1 | 0.00% | 0.00% | 0.00% | Q4 2014 | Q4 2014 | 1 |
This page lists all the filers that currently own ARCH COAL INC or have owned ARCH COAL INC in the past.