Essar Energy , Cairn Energy and Hargreaves Lansdown are all likely to be demoted on Wednesday from the FTSE 100 <.FTSE> blue-chip share index.

Moving in the opposite direction, specialty chemicals firm Croda International looks set to join the large-cap index for the first time, while Aberdeen Asset Management and oil services firm John Wood Group are tipped to rejoin the big guns.

All the likely changes are based on the individual companies' market capitalisations at the close on Friday, March 2, with the information having been provided by FTSE.

The changes will be formally announced by the FTSE compiler after the market close on Wednesday, March 7, after being confirmed by a FTSE committee and using the closing prices from March 6. They will be made effective 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 into 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 <.FTMC>.

ESSAR NAILED ON

India-focused energy firm Essar Energy looks the most nailed-on change, with its stock having plunged over 116 percent since the last quarterly index review on December 7.

Essar's slide was exacerbated in February by its full-year results -- a 10 percent fall in core earnings, missing expectations and prompting a number of broker downgrades.

Essar joined the index in June 2010 with a number of other commodity companies.

The likely demotion of oil explorer Cairn Energy would also modestly dilute the heavy commodity bias of the blue-chip index, though Cairn's performance has actually improved by 8 percent since the time of the last quarterly review.

However, the outperformance of a number of FTSE 250 stocks has pushed the oil explorer's shares into demotion territory.

Cairn shares have seen the benefits of a big return of cash to shareholders in January after the sale of its stake in Cairn India, but that has been balanced by strategy concerns and disappointing updates from its drilling programme in Greenland.

Wealth manager Hargreaves Lansdown has seen its shares fall 5 percent since December, a big underperformance compared with a 6 percent rise by the FTSE 100 index over the same period.

Its shares have been volatile in the quarter, falling about 3 percent in January before gaining over 10 percent for the period at its late February peak after first-half results.

But some negative broker comment since that high has hauled Hargreaves back down to earth, threatening its blue-chip status.

CRODA CROWNED

Mid-cap Croda, by contrast, has added 12.5 percent in the quarter, helped by a leg-up in late February after a near 26 percent jump in full-year pretax profit, leading brokers to raise their target prices.

Wood Group has been on a fairly steady upward track, gaining almost 14 percent since December 7, helped by news of contract extensions as activity in energy services picked up, with takeover interest also underpinning the sector.

Aberdeen Asset Management has benefited from an improving performance by equity markets over the quarter, with the group having seen a rise in total assets in its last trading update in January, despite further net client outflows from its funds.

Aberdeen shares have gained over 17 percent over the quarter, outperforming a 14.2 percent rise by the FTSE 250.

Four other changes could be likely to the mid cap index, according to FTSE, with commodity stocks Avocet Mining , Petra Diamonds
and Ruspetro all potential new entries, and income fund NB Global Floating Rate expected to be promoted from the FTSE Small Cap <.FTSC> index.

Allied Gold Mining , Impax Environmental Markets , JP Morgan European Smaller Companies Trust and Unite Group are the FTSE 250 firms in danger of relegation to the small caps.

(Editing by Will Waterman)