Bill Miller started to build up the position in ProShares Trust - ProShares UltraPro QQQ 3x Shares in Q1 2018 and continued to invest until Q2 2018. Since then they sold 336k shares. The investor sold all their shares in Q4 2018 and doesn't own any shares in ProShares Trust - ProShares UltraPro QQQ 3x Shares anymore.