I have two sheets of data. Sheet A will have three pieces of
information (Account Number, Ticker, Shares) and Sheet B across the
top lists accounts and below lists tickers (up to 1400).

Sheet A (example)

1000, XXX, 1
2000, YYY, 1


Sheet B (example)

1000, 1500, 2000
AAA, AAA, BBB
CCC, CCC, CCC
XXX, XXX, XXX

In column D I need to look up in Sheet B if for Account 1000 XXX is
listed below etc.

Any help will be appreciated.