We complete our look at the first-half winners and losers by putting the spotlight on the big guns.

If you haven't already, be sure to investigate the climbers and fallers on AIM and the FTSE 250.

The FTSE 100 has endured the rockiest of rides, starting the year just above 6000 before plunging to below 5600 in mid-March. The rollercoaster ride continued until the end of June, with the index flirting with the 6100 mark before sliding to around 5650, and then launching a last-ditch rally which continued into the second half.

** TOP FIVE WINNERS **

ARM Holdings (38.91 per cent rise in the first six months)

The top-performing stock in the FTSE 100 for the first half of the year was technology firm ARM Holdings, with its share price up more than 38 per cent at around 605p.

The company kick-started the year when it announced on 6 January it had gained support from tech giant Microsoft for its system on a chip architectures for the next version of Windows.

ARM's fourth-quarter results for 2010, which it reported in February, showed pre-tax profit up by almost 50 per cent at £47.6 million. And for the full year it announced its highest ever pre-tax profit, up a whopping 73 per cent from the year before at £167.4 million, compared to £96.8 million.

Warren East, chief executive officer for the company, said: 'ARM continues to sign licences with influential market leaders in an increasingly digital world, and as the industry chooses ARM technology in a broadening range of electronic products, it further drives our long-term royalty opportunity.'

In the first quarter of 2011, the Cambridge-based firm didn't falter either.

Pre-tax profit was up 35 per cent at £50.8 million, from £37.6 million in 2010, and Broadcom and LG Electronics were the latest companies said to have signed subscription licences for ARM's technology.

The company's outlook for the year, notwithstanding uncertainty surrounding the economic impact of the Japanese earthquake on the semiconductor industry supply chain, is for dollar revenues to be at least in line with current market expectations.

Aggreko (30.16 per cent)

Temporary power supplier Aggreko took silver medal for first-half performance, as it carried momentum from the end of 2010 into the new year.

In fact, things just got better and better for the firm, which noted 'the rate of underlying growth seen in the first quarter has accelerated in the second quarter' in a 20 June update, having reported a 24.6 per cent rise in full-year pre-tax profit for the 12 months to end-December.

A pair of contract wins and a New Zealand-based acquisition helped Aggreko into second spot, even overcoming a dip in its share price towards the end of the period.

Burberry (29 per cent)

Luxury fashion brand Burberry shook off concerns at the start of the year that it would be adversely affected by a slump in demand in its significant Japanese market and welcomed a 29 per cent increase in its share price in the six months to 30 June.

A trading update in January informed investors that sales at the tail end of 2010 were strong for both retail and wholesale and across every product division and region. As a result, the company predicted pre-tax profit for the 2010/11 financial year to be at the top end of expectations.

Following the earthquake and tsunami in Japan, shares in Burberry suffered a momentary blip, down 4 per cent on the first trading day after the quake. This is because Japan is the third-largest market for luxury goods globally, after the US and China.

But fears for the firm were short-lived and in April it updated investors on its trading for the six months to 31 March. Total revenue for the period was up 30 per cent at £860 million, with growth in China spearheading the positive performance.

The company is due to report first-quarter 2011/12 results on 13 January and analysts are predicting further sales growth, but add the first quarter will be the poorest of the year. Most have also taken a 'hold' stance ahead of the results as they believe most of the positive expectations are already priced into the stock.

Eduard Crowley, analyst for Exane BNP Paribas, said: 'We praise Burberry's strong track record and believe the 20 per cent earnings per share compound annual growth rate story is a unique feature in the luxury space at this time in the cycle, somewhat justifying a premium. We, however, believe this is more than priced in, with the stock trading on a 2011 equivalent calendarised EBITDA of 18 times versus 13.3 times for the sector.'

Citigroup and UBS also set Burberry as a hold, with target prices of 1,300p and 1,255p respectively.

Land Securities (26.48 per cent)

Shares in Land Securities notched up the best gains in the real estate sector since the turn of the year, slipping briefly from 685p in February before staying on a fairly consistent upward trajectory until June.

Having entered 2011 'with a clear plan', the firm's January interim management statement disappointed somewhat, before full-year results in mid-May really put the cat amongst the Trafalgar Square pigeons, as it benefited from a recovery in Central London.

Rises across the board in pre-tax profit, NAV per share, earnings per share and dividend all triggered a stellar second quarter, with shares going from around the 750p mark to end June – and the first half – at just below 850p.

Indeed, following those results, analysts at Collins Stewart heralded them 'excellent figures', adding that they expected shares to 'improve significantly' as a result. Its forecasts were lifted from 773p to 826p for the actual NAV and from 5.9 per cent uplift to 9.7 per cent for the overall portfolio.

Shire Pharmaceuticals (26.05 per cent)

Pharmaceutical company Shire Pharmaceuticals has also had a strong first half of the year. In the last six months its shares have ticked up more than 26 per cent to sit at around 1,998p.

At the start of the year the company announced product sales up 16 per cent at $3.12 billion (£1.96 billion) and total revenue up 15 per cent at $3.47 million (£2.15 million).

Angus Russell, chief executive officer for the firm, said at the time: '2010 was an outstanding year for Shire with the business performing exceptionally well on all fronts. Both our speciality pharmaceuticals and human genetic therapies business showed excellent growth.'

In April, results for the three months to 31 March showed products sales up by 24 per cent to $889 million (£551 million), while total revenue for the period was $972 million (£602 million), 19 per cent up on the same period last year.

Sales of Attention Deficit Hyperactive Disorder treatments Intuniv, Vyvanse and Adderall XR were all up and the firm said the ADHD market in the US as a whole showed good growth. Rare disease treatments also continued their strong performance, representing 30 per cent of total product sales.

The company is working on gaining regulatory approval in both the US and Europe for some of its drugs and is researching new uses for some of its other products. It completed a couple of acquisitions during the period too, which demonstrates a desire to grow through both organic and expansionary means.

But a cloud on the horizon is the number of lawsuits the firm currently has ongoing, relating to alleged patent infringements by other companies on its medicine Vyvanse. The marketing exclusivity of Vyvanse runs out in 2012 and if Shire doesn't win the patents battles, generic versions of the drug are likely to be produced and could sap some of the company's revenue in the process.

** TOP FIVE LOSERS **

Essar Energy (-29.47 per cent)

India-focused Essar Energy, which only listed in May last year, has seen its share price fall almost 30 per cent in the first six months of the year – the biggest drop of any FTSE 100 company.

After disappointing maiden results last year, it started this year a little more positively, gaining a boost in January from its 87 per cent owned subsidiary Essar Oil, which announced revenue up 21 per cent in the three months to 31 December.

In March pre-tax profit up 28 per cent to £365.5 million for the year to 31 December was not enough to convince investors of the stock's potential and it lost 7 per cent of its value. The main reason for this was the admission by the firm that its expansion programme had suffered a number of setbacks and heavy monsoon rains had delayed construction of three new power plants.

The Indian government's delay in approval for Essar's planned coal mines also held the firm back as it had to supply its new coal plant with more expensive state-run coal.

But the firm insists it is closer to its production targets than it seems.

The company's aim is to expand its output 10 times to 11 gigawatts over the next few years by tapping into India's need for energy as it continues to industrialise.

In the mean time the firm said it hopes to complete its acquisition of Stanlow refinery from Shell for $350 million (£217 million) at its AGM on 18 July. This refinery's chief purpose will be to give the company a UK base and diversify it from its core interest in India.

International Power (-26.49 per cent)

Fellow energy stock International Power also had a tough time of it in the first half of the year, falling more than 26 per cent.

Events took a turn for the worse for the giant in February when it announced that it had merged its business with France's second largest utility, GDF Suez, which saw the French company take a 70 per cent stake.

And just a month later it unveiled a downturn in its full-year underlying profit, with Europe, the US and Australia all suffering a decrease. The company said US profit was impacted by a planned outage and lower write back of fair value provisions at Coleto Creek, while in the UK low gas prices wreaked havoc.

As a result, shareholders lined their pockets with a full-year dividend of 10.91p per share, down on the 12.53p they raked in the previous year.

A more upbeat outlook in April, when it said it continued to make good progress on its project pipeline, managed to rouse investors and send its shares back above the 332p mark, but the turnaround proved short lived.

By mid-May, the company's share prices had taken a sharp fall amid an announcement that it had sold its 33.3 per cent interest in the 420 megawatt T-Power CCGT power plant in Belgium to Japanese conglomerate Itochu.

A month later it told investors it had entered into a joint venture agreement with PT Supreme Energy and Marubeni Corporation for the development of the Rantau Dedap geothermal project in Indonesia.

Since period end, the Australian government's proposal on climate change spurred a climb in the company's shares after it responded positively to the news of carbon credits and said the plan was expected to be cash flow positive over the initial five year period.

Analysts at both UniCredit and Deutsche Bank list International Power as a buy, with respective target prices of 365p and 378p. UniCredit analysts said: 'Despite recent underperformance we believe that the growth story remains intact and that a combination of exposure to high-growth emerging markets, low commodity price exposure and a strong balance sheet is an attractive investment proposition.'

Lonmin (-26.09 per cent)

The six-month chart of platinum producer Lonmin's shares does not make for pretty reading, featuring enough downhill slopes to keep Eddie the Eagle interested.

Starting the year over 1,850p, Lonmin ended around the 1,400p mark following steady but unspectacular production updates that were then exacerbated by strike action at its Karee operations in South Africa. The week-long industrial action eventually led the FTSE 100 firm to reduce its full-year guidance to sales of around 720,000 platinum ounces for the year to 30 September 2011, having initially expected to make up the lost production in the second half of the year.

With the commodities bubble looking fragile of late, it'll be hoping it can turn things around from now until December.

Eurasian Natural Resources (-25.43 per cent)

Like its sector rival Lonmin, it was a steady story of decline in the first half of 2011 for Eurasian Natural Resources.

The firm, which is largely focused in Kazakhstan, warned at the end of 2010 that revenue growth was being affected 'by a slowing pace of increase in prices and volumes' compared to the first half of the year.

Its next update – ENRC's fourth quarter – was greeted with another sell-off, despite it stating that it was operating at 'effectively full capacity' in that timeframe.

A brief spike in the back-end of March following decent full-year results proved short lived, as did gains courtesy of speculation commodities trader Glencore was eyeing a takeover bid.

Lloyds Banking Group (-25.42 per cent)

The worst performing bank stock and fifth worst performing stock in the FTSE 100 was Lloyds Banking Group, which has shed more than 25 per cent of its share value in the first half of 2011.

Lloyds's weaknesses, along with those of the rest of the banks, have been well catalogued and a lot of them stem from its (some would say ill-advised) takeover of HBOS at the height of the financial crisis.

But in February of this year, the group announced its full-year results for 2010, which showed a return to profitability on a combined business basis, with profit before tax of £2.2 billion. This compared to a loss of £6.3 billion in 2009, so could be considered quite the turn around.

Initially after these results the stock ticked upwards towards 70p, but it followed a steady downward trend from March through to the end of June, where it finished at 44.5p.

This was not helped in May by the release of its interim management, which revealed pre-tax profit down to £284 million in the three months to 31 March, compared to £1.1 billion in the same period in 2010.

Many of the reasons for Lloyds's weakness are true for the entire banking sector. For example, concerns over the eurozone debt crisis regularly lead investors to plunder bank stocks as they consider the potential knock on effect of European governments defaulting on bonds.

News flow surrounding regulation of the banks can also have a short term impact on the stock's performance and the redress of the PPI scandal has also taken a big dent out of the firm's revenue. Additionally, as Britain's biggest mortgage lender, Lloyds's performance is tied up with the strength of the housing market and the ability of borrowers to repay their mortgages.

Despite all this, both UBS and Nomura have Lloyds listed as a 'buy', with a target price of 73p and 80p respectively.

After Lloyds released a strategic review on the 30 June, John-Paul Crutchley, analyst at UBS, said: 'Lloyds's strategic review is a comprehensive document that, in our opinion, does not change near-term guidance and reaffirms our longer-term expectations.

'The market should be comfortable that there is no kitchen sinking, which implies that tangible book should have troughed, longer term street expectations look too conservative, asset quality is reaffirmed and you can therefore expect a rising return on equity on a rising book value. Given that the stock is trading at 80 per cent of book, we think the company is materially undervalued.'