Hi. I have two separate lists, one with company sector(1) and one without (2). I have merged the two lists and want to populate the (2) list with the correct sector(from the corresponding (1) list). The sheet has 140000 entries so copy and paste is simply killing me.

Can anyone help me with a formula to solve this please??
COLUMN A Column B

2Calor Gas Ltd
2Calor Gas Lt[/B]d
1BUSINESS & INDUSTRIAL 1Calor Gas Ltd

2Cambridge Manufacturing Company Ltd
2Cambridge Manufacturing Company Ltd
2Cambridge Manufacturing Company Ltd
2Cambridge Manufacturing Company Ltd
2Cambridge Manufacturing Company Ltd
2Cambridge Manufacturing Company Ltd[/B]
1PHARMACEUTICAL 1Cambridge Manufacturing Company Ltd