After-hours movers:

WK Kellogg (KLG) rose 49% after WSJ reported Ferrero plans a deal for the company valued at $3 billion.

Ultragenyx Pharma (NASDAQ: RARE ) fell 27% after the company announced its Phase 3 Orbit study in osteogenesis imperfecta patients will continue to final analysis rather than stopping early for efficacy.

Costco (NASDAQ: COST ) stock rose 1% after the warehouse retailer reported an 8% increase in net sales for June, showing continued strong consumer demand.