UK stocks opened in the red on Tuesday as investors continue to tread cautiously ahead of a Federal Open Market Committee (FOMC) decision and vote on Scottish independence on Thursday. The London FTSE 100 index is trading 33 point off at 6,770 in early deals after a subdued session on Monday.

Fallen 'fast fashion' star ASOS' (ASC:AIM) annus horibilis continues, the online retailer giving up 12.8% at £21.11 as its latest trading update triggers another round of downgrades. Fourth quarter trading to end-August was in-line with expectations, though sales and margins were hit by a fire at the online retailer's Barnsley warehouse. However, the latest disappointment over the the need for investment in cutting prices, as well as in technology and infrastructure, will result in flat profits for the year to August 2015, driving a sharp downgrade of between 25-30%.

The market has given an apparent thumbs up to the redesign of the Financial Times, marking shares in its publisher Pearson (PSON) 2.3% to £12.34. The changes are part of a wider shift in focus to the FT's digital operation.

Weak economic data from China has driven Brent crude oil prices to a 26-month low below $97 a barrel and this is putting pressure on FTSE 100 oil stocks Tullow Oil (TLW) and Petrofac (PFC) - down 2.6% to 682.5p and 2.2% to £10.32 respectively.

A slowdown in Thomas Cook's (TCG) German business puts shares at the tour operator under pressure with stock falling 6.2% to 121.9p. Earnings before interest and tax (EBIT) of between £315 and £335 million pounds are expected in the year to the end of September but the group's pre-close statement also noted that in Germany, average selling prices are 3% lower than last year due to an increase in market capacity to short and medium haul Summer destinations.

Managed services data centres operator Iomart (IOM:AIM) crashes by close on 13% to 229p as private equity-backed Host Europe pulls out of takeover talks. A 300p to 325p per share deal had seemed likely. But the running Shares Play of the Week's typically robust trading update should give investors cause for optimism.

A headline revenue decline of 17% sparks a sell-off in shares of compound semiconductors specialist IQE (IQE:AIM), the stock down 9% at 18.25p. Currency effects and some induistry dstocking are behind the fall, although Canaccord retains its full year earnings before interest, tax, depreciation and amortisation (EBITDA) estimates at £27.7 million, and target price of 35p.

Plus size fashion retailer N Brown (BWNG) sheds 4.2% at 388.15p on a mixed second quarter trading update. Though like-for-like sales fell 3.2% in the 15 weeks to 13 September, the decline masks the improving quality and profitability of N Brown's sales as CEO Angela Spindler accelerates positive strategic changes and the retailer still expects to hit full-year forecasts.

US and EU sanctions designed to hurt Russia boomeranged on Virgin Islands-headquartered oil and gas supplier Thalassa Holdings (THAL:AIM). The stock slumps more than a quarter, or 52p, to 129p on contract delays with Russian clients, weakening profitability in the half year to June and an uncertain outlook.

Slower than expected progress at Porta Communications’ (PTCM:AIM) financial and charity advertising divisions dented management’s hopes for a move into profit in the six months to end-June. Basic earnings per share (EPS) were -0.2p. The small cap trades down 8% at 9.2p.

News that chief executive Greg Fitzgerald will leave heavy construction specialist Galliford Try (GFRD) by the end of 2015 at the latest offsets upbeat final results. The shares dip 1.6% to £12.18. Galliford sees revenues in the year to June 2014 rise 21% to £1.768 billion while profit before tax added 28% to £95.2 million and earnings per share rose 32% to 94.6p.

In its interim management statement, housebuilder Crest Nicholson (CRST) noted a moderation in sales over the past few months in line with normal seasonal trends and even though the group's financial position remains healthy and the board is confident of delivering a strong year end performance, shares slip 4.2% to 322.7p.

Elsewhere in the housebuilding space, full year results from Mar City (MAR) see shares adding 2.2% to 117p after the group posted a 212% rise in underlying operating profit to 3.422 million in the year to the end of June.

Medical technology concern EKF Diagnostics (EKF:AIM) rises 11.9% to 24.6p on a positive outlook for the second half after losing £2.4 million before tax in the opening six months of the year.

Blood gas monitor maker Sphere Medical (SPHR:AIM) improves 5% to 26p on launching its Proxima device today after years of development.

Heart-monitor maker LiDCO (LID:AIM) falls 7.9% to 13p on pre-tax losses in the first half widening to £190,000 on sales 16% down in its core UK market.

Sexual health drug-maker Plethora (PLE:AIM) gains 2.5% to 10.3p as distributor Recordati agrees to sell its product in Europe, Russia, Turkey and parts of North Africa.

Issue Date: 16 Sep 2014