British Airways has returned to the UK's prestigious FTSE 100 share index, just three months after being demoted.

During the last reshuffle of the FTSE 100, BA was relegated to the FTSE 250 index for the first time since it was privatised in 1987.

Accompanying BA into the FTSE 100 are retail property firm Liberty International and leisure group Whitbread.

But telecoms group Cable & Wireless, steelmaker Corus and the Anglo-Australian engineering group Brambles have all fallen into the FTSE 250.

The changes will take effect at the close of trade on 20 December.

Smoother ride

BA's share price has soared by 67% over the past two months.

Investors have been encouraged by signs that the airline's restructuring plan is working.

BA has cut thousands of jobs, reduced capacity and slashed fares in an attempt to compete with the budget airlines.

Last month it reported a jump in profits to �245m for the three months to the end of September.

On the way out

Cable & Wireless shares halved earlier this week on worries about the firm's financial position.

Investors shunned the shares after C&W said that it had a potential �1.5bn tax liability after receiving a "junk bond" ranking from credit rating agency Moody's.

Steel maker Corus has seen its share price fall sharply following last month's collapse of its planned merger with the Brazilian firm Companhia Siderurgica Nacional.

Brambles' share price has been hit by a number of profit warnings, following problems with the company's European pallet division.

Tech cheer

Troubled holiday group MyTravel and health and fitness firm Fitness First are among the companies dropping out of the FTSE 250 index.

But there is some good news for some former starts of the technology share boom.

Lastminute.com and software group Autonomy have been promoted into the FTSE 250.

Quarterly reshuffle

The make-up of the FTSE 100 share index is reviewed every three months.

A company's stock is promoted into the FTSE 100 if the firm's market capitalisation ranks in the top 90 at the close of business on the last day of trading before the review - in this case Tuesday.

If a stock is ranked 111th or lower, the company is ejected from the index and it drops into the FTSE 250.