Why do stocks go up after hours?

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Tags

1. #securities
2. #stock
3. #closes
4. #investor
5. #hours
6. #exchange
7. #period
8. #periods
9. #market
10. #regular
11. #occurs
12. #major
13. #through
14. #after
15. #investors
16. #exchanges
17. #outside
18. #standard
19. #trading