* Croda and Aberdeen Asset promoted to UK blue chips
* Changes effective from market close on March 16
By Jon Hopkins
LONDON Mar 7 (Reuters) - Essar Energy and Cairn Energy will lose their blue-chip status and be demoted to the FTSE 250 index, indexes compiler FTSE said on Wednesday.
Specialty chemicals firm Croda International and Aberdeen Asset Management will be promoted to the FTSE 100 index to replace them, FTSE added.
The changes were confirmed by a FTSE committee on Wednesday, using the closing share prices from Tuesday, and will be effective from after the market close on Friday, March 16.
Companies outside the FTSE 100 that grow to rank among the 90 largest by market capitalisation are automatically promoted to the blue-chip index, while the FTSE 100 firms with the lowest value, or that fall to 111th spot or below, drop into the FTSE Midcap 250 index.
Four other changes will be made to the FTSE 250 index, FTSE said, with commodity stocks Avocet Mining, Petra Diamonds, and Ruspetro, plus income fund NB Global Floating Rate all joining the FTSE 250 index.
Going the other way, Allied Gold Mining, Impax Environmental Markets, JP Morgan European Smaller Companies Trust and Unite Group will all be demoted to the FTSE Small Cap index.