Lucas Downey says there's a lot "under the surface that has been working" outside the Mag 7. Among the stocks he sees continuing momentum: memory chips. He says Micron (MU) "kicked everything off" by showing its earnings acceleration with a bottleneck "so severe" that makes it an attractive long-term stock. Lucas notes SanDisk (SNDK) and Lam Research (LRCX) as his number two and three picks.