TradeID Stock   Timestamp
1       GOOG    2014.03.03 09:13:59.054
2       GOOG    2014.03.03 09:28:12.003
3       GOOG    2014.03.03 09:28:18.199
4       GOOG    2014.03.03 09:52:03.628
5       GOOG    2014.03.03 11:18:52.629
...

Stock   Timestamp               Bid         Ask
GOOG    2014.03.03 08:02:34.297 102.21      102.41
GOOG    2014.03.03 08:02:40.118 102.32      102.42
GOOG    2014.03.03 08:02:44.090 102.33      102.43
GOOG    2014.03.03 08:03:20.197 102.34      102.44
GOOG    2014.03.03 08:05:09.325 102.35      102.45
...

aj[
    `Stock`Timestamp;
    Trades;
    update TimestampPrice:Timestamp from Prices  / let's me track which price gets joined
]

TradeID Stock   Timestamp                TimestampPrice             Bid     Ask
1       GOOG    2014.03.03 09:13:59.054  2014.03.03 08:05:09.325    102.35  102.45
2       GOOG    2014.03.03 09:28:12.003  2014.03.03 08:05:09.325    102.35  102.45
3       GOOG    2014.03.03 09:28:18.199  2014.03.03 08:05:09.325    102.35  102.45
4       GOOG    2014.03.03 09:52:03.628  2014.03.03 08:05:09.325    102.35  102.45
5       GOOG    2014.03.03 11:18:52.629  2014.03.03 10:31:45.043    102.24  102.35
6       GOOG    2014.03.03 11:33:52.021  2014.03.03 10:31:45.043    102.24  102.35