Why do stocks spike after hours?

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Tags

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2. #markets
3. #ownership
4. #after
5. #hours
6. #shares
7. #interfere
8. #normal
9. #stock
10. #place
11. #exchange
12. #spike
13. #trading
14. #companies
15. #where
16. #these
17. #trades
18. #kinds
19. #registered