Profit warning and accounts worry send Helphire into a skid

Helphire, which provides replacement cars for motorists involved in crashes, said profits this year would be lower than anticipated as fewer drivers took to the roads because of high petrol prices.

To pile on the woes for its investors, disaster-struck Helphire has found out that it may have overstated the cash it was due from its insurance-company debtors by about £25 million. Its shares crashed 8.4p to 4.8p.

Shares in London ended a miserable week with another fall, with the FTSE 100 index sliding 16.95 points to 5903.03. But on an unusually busy Friday for corporate news, the bevy of blue-chip companies updating the market mostly cheered investors.

Admiral took gold on the benchmark, surging 79p to 1741p after the car insurer delivered a 56% jump in revenues in the first quarter. Royal Bank of Scotland landed silver, climbing 1.4p to 41.9p, as Stephen Hester, its hunting garb-donning chief executive, made positive noises on outlook. Signs of progress in the state-backed lender's business recovery plan put a smile on investors' faces, although analysts continued to mutter about the dire situation in Ireland and remain divided on whether the shares look attractive.

Espirito Santo's Joseph Dickerson says buy, Ian Gordon of Exane BNP Paribas reckons hold and Seymour Pierce banking guru Bruce Packard has a reduce rating on the bank.

International Airlines Group claimed bronze after the British Airways owner saw losses narrow faster than analysts had expected. The airline, 5.7p stronger at 251.7p, was also boosted by a sharp drop in the oil price, which also pushed cruise operator Carnival up 77p to 2627p and Tui Travel 4.5p higher to 246.4p.

Unsurprisingly though, it sparked a sell-off in the titans of crude, with Royal Dutch Shell off 45p at 2198p, Arctic explorer Cairn Energy down 8.8p at 413.9p and BG Group 23p lowers at 1383p. Meanwhile, sliding metal prices hit the mining giants. Randgold Resources retreated 88p to 4814p, Kazakhmys fell 23p to 1237p and platinum producer Lonmin lost 19p to 15171⁄2p. With silver plunging to a six-week low, Mexican precious metals producer Fresnillo shed 41p to 1404p.

But Arm Holdings topped the laggards list, down 111⁄2p at 5551⁄2p as investors continued to fret about the threat posed by rival Intel's new chips.

On the mid-tier, Laird jumped 51⁄2p to 143p. The electronics group, which supplies companies including Nokia and Samsung, saw a pick-up in orders and sales in April, and is benefiting from its acquisition spree. However, the Japanese triple catastrophe will knock about $5 million (£3 million) off 2011 revenues.

"Our own sales into Japan itself (as opposed to sales to our Japanese customers) remain relatively small, and we have taken actions to mitigate any supply chain issues arising from our Japanese sourced components," the company said.

Standard Life has been splashing out on emeralds, raising its stake in miner Gemfields to 4.8%. Gemfields shares were flat at 18.6p.