ticker,when,price
APPL,2001-01-01 00:00:00,1
APPL,2001-01-01 00:01:00,2
APPL,2001-01-01 00:02:00,3
MSFT,2001-01-01 00:00:00,1
MSFT,2001-01-01 00:01:00,2
MSFT,2001-01-01 00:02:00,3
GOOG,2001-01-01 00:00:00,1
GOOG,2001-01-01 00:01:00,2
GOOG,2001-01-01 00:02:00,3