The FTSE 100 celebrates its 30th birthday on January 3, we take a closer look at the UK’s leading index over the past three decades

The FTSE 100 launched on January 3 1984 with a base level of 1,000, replacing the FT30 as the main indicator for the performance of companies listed on London Stock Exchange (Other OTC: LDNXF – news) (LSE).

The current market cap of the FTSE 100 constituents is £1.87 trillion – up from £164bn in December 1985 (the first available data).

The FTSE 100 was created at the LSE headquarters in 60 Threadneedle Street (above), its historic home, where it oversaw the “Big Bang” and rapid growth of the City.

But in 2004 it moved to its current base of Paternoster Square (below), just up the road, where it has seen the credit crunch and the longest and deepest recession since the the Second World War.

The FTSE 100 made many happy returns in its final year in its 20s, closing at 6749.09 on December 31 – up 14.4pc for the year – it’s best rise since 2009.

That means means the blue-chip index has risen 549.9pc since it launched 30 years ago. That’s an average of an 18.3pc rise a year – not too shabby.

But while the average yearly return has been impressive, like most 30-year-olds, the main index has seen its fair share of highs and lows over the years.

It reached its peak shortly before its16th birthday, hitting 6950.6 on December 30 1999, while its best year was in 1997 when it rose 24.69pc over the 12 months.

10 biggest FTSE 100 rises (in one day) Date Close % rise 24/11/2008 4152.96 9.84pc 19/09/2008 5311.33 8.84pc 13/10/2008 4256.9 8.26pc 29/10/2008 4242.54 8.05pc 21/10/1987 1943.8 7.89pc 08/12/2008 4300.06 6.19pc 13/03/2003 3486.9 6.08pc 10/04/1992 2572.6 5.59pc 20/10/2008 4282.67 5.41pc 17/10/2008 4063.01 5.22pc But what goes on must come down. 2008 saw the largest annual fall , with the index plummeting 31.33pc, as banks collapsed and the credit crunch hit.

The main index finally hit its lowest point in the past five years on March 5 2009, falling to 3529.86.

10 biggest FTSE 100 falls (in one day) Date Close % fall 20/10/1987 1801.6 12.22pc 19/10/1987 1052.3 10.84pc 10/10/2008 3932.06 8.85pc 06/10/2008 4589.19 7.85pc 15/10/2008 4079.59 7.16pc 26/10/1987 1684.1 6.19pc 11/09/2001 4745.98 5.72pc 06/11/2008 4272.41 5.7pc 22/10/1987 1833.2 5.69pc 18/01/2008 5578.23 5.48pc

GlaxoSmithKline (Other OTC: GLAXF – news) , the drug maker, is one of the 19 companies that were in the FTSE 100 from the outset and have never dropped out. Photo: Alamy

But while it may have been a bumpy ride at times, there are 30 companies in the FTSE 100 that were there at the start and are still in today and 19 that have always been in it. They are:

(* means they have been a constant constituent)

Meanwhile, some companies have worked their way up from the small cap index, all the way to the top flight. They are:

Aberdeen Asset Management (Other OTC: ABDNF – news) , Amec (Other OTC: AMCBF – news) , Babcock International Group, Melrose (Stuttgart: 2NM.SG – news) , Tullow Oil (LSE: TLW.L – news) and Weir Group (Dusseldorf: 42W.DU – news)