Investors change tack in mid-morning trade on Friday propping up London share prices after initial declines across the market. The clue-chip FTSE 100 index adds around 25 points, or 0.35%, to 6,679 with similar gains being chalked-up across the wider FTSE All-Share index. But midcaps struggle to overcome several negative corporate announcements from FTSE 250 companies, including miner Lonmin (LMI) and Aggreko (AGK).

Lonmin slumps close on 8% to 69.75p as it warns of a period of 'significant short term pain' as it cuts costs in then face of collapsing platinum prices. CEO Ben Magara says the group is attempting to defend value for all stakeholders by taking swift, decisive and difficult measures, although that fails to make the news any easier to swallow for shareholders.

Aggreko, meanwhile, becomes the latest equipment hire firm to hit the buffers as profits weaken. Security challenges in Yemen and contraction in Aggreko’s North American oil and gas-related businesses mean 2015 interim and full year results will be below market expectations, chief executive Chris Weston says in a trading update, sparking a 16% plunge in the share price to £11.96.

Aggreko’s profit warning comes on the back of similar statements from more UK-focused industry peers Speedy Hire (SDY) (click here) and HSS Hire (HSS:AIM) (click here). US-focused Ashtead (AHT) is tumbling in sympathy, down 2.5% to 951p after an earnings downgrade from analysts at Bank of America-Merrill Lynch yesterday.

Adding to the midcaps malaise is bookmaker Ladbrokes (LAD), which slips 1% to 127p, with investors seemingly undecided about confirmation that the company plans to push ahead with its merger with Gala Coral, a deal that will create a bookmaking giant worth £2.3 billion, closing the market cap gap on the sector's biggest player Paddy Power (PAP). Ladbrokes is offering 93 million new shares - representing 10% of the company - to investors to fund the deal, which will create the UK's biggest high street betting agent. Chief executive Jim Mullen also unveils a three-year investment programme that aims to grow revenue contribution from its digital business from 18.6% to 30%.

Among other big movers, generic drug and related ingredients maker Beximco Pharmaceuticals (BXP:AIM) advances 8.7% to 18.7p on a 39.9% rise in pre-tax profits to £8.3 million in the six months to the end of June. New product launches and moving into new geographical markets contributed to the income gains with management remaining upbeat on future earning potential.

Rocketing higher is building services consultancy microcap Greka Engineering & Technology (GEL:AIM) as it posts continued growth in all of its key metrics at the interim stage. The company says it is benefiting from increases in gas processed, electricity generated and process engineering, and the shares surge 13% to 0.65p, nudging the firm's market value fractionally beyond £4 million.

Elsewhere, Diageo (DGE), purveyor of Johnnie Walker whisky, Smirnoff and Guinness, sheds 1.8% on news of an investigation into its accounting practices by US market regulator the Securities and Exchange Commission (SEC). Enquiries by the SEC centre around ‘channel stuffing’, a practice by which a company increases profits by shifting larger than usual amounts of product to third-party distributors, according to the Wall Street Journal.

Mobile giant Vodafone (VOD) is also among the blue-chips risers on Friday, adding a little more than 2% to 237.45p, as it reports a positive start to the year. First quarter revenue hits £10.1 billion, and while that's largely flat at the headline level, the figure represents 3.3% growth in underlying organic terms.

After a 4% rise at the market open, FTSE 100 miner Anglo American (AAL) eases back to record a 1% gain at 811.3p after better-than-expected results and no cut to its dividend.

A deepening collaboration with aspirational middle-class trader John Lewis sees shares in logistics specialist Clipper Logistics (CLG) advancing 5.8% to 227p as the £222.3 million cap looks to develop fulfilment solutions for the retailer's click and collect orders.

A 2% rise in gross written premiums to $1 billion lifts non-life insurer Beazley (BEZ) 3% higher to 330.2p.

Issue Date: 24 Jul 2015