Supermarkets and mining shares are sending the UK market lower for the third day, on course for its lowest level since the middle of August.
Previous worries - the effect of the continuing protests in Hong Kong, the air strikes on Isis - remained, while further signs of weakness in the global economy added to investors' caution.
The FTSE 100 is currently 22.13 points lower at 6601.59 following disappointing PMI surveys for September from China, Germany and the UK.
The Chinese data in particular has pushed mining shares lower, with Anglo American down 23.5p to 1360.5p and Antofagasta 8p lower at 713p.
Tuesday's plunge in the oil price - linked to the continuing strength of the dollar in the expectation of US interest rate rises - has also affected the commodities sector. Despite Brent crude edging up 0.2% to $94.86 a barrel, the recent falls below $100 have unsettled investors in oil companies.
Tullow Oil has slipped 12.5p to 632p while Royal Dutch Shell A shares are down 24p at 2334.5p.
BG has fallen 28p to £11.12, not helped by Credit Suisse cutting its price target to £10.50 from £11.15. It said:
Operational estimates remain unchanged for now, despite the 'extended' uncertainty or riskiness of its production curve well into 2018. At this stage, we adjust for these 'risk factors' by taking a 15% discount to our net asset value (from 10%). Perhaps the discount should be larger as the 'risk factors' are related to Brazil & Australia.
Among the supermarkets, J Sainsbury has lost 8.7p to 242.8p despite its figures coming in slightly better - or at least less worse - than expected. It cut its full year sales forecast and said it would assess its dividend policy as part of a strategic review.
Tesco is down 5.05p to 181.15p after it said the Financial Conduct Authority had launched a full investigation into the accounting scandal at the supermarket.
Morrisons is also down, 7.6p lower at 160.7p although 4p of this is due to the shares going ex-dividend.
But following its recent falls, Royal Mail has recovered 16.1p at 408.3p as UBS raised its recommendation from sell to neutral with a 400p price target, down from 450p. UBS said:
Royal Mail faces a number of challenges, including modernising its network, managing the decline in letter mail volumes, the threat from competition in both letter and parcel, as well as dealing with a highly fixed cost base. We believe Royal Mail faces particular issues with having a highly unionised, relatively well paid workforce at a time when its revenue visibility is low and when both the letter and parcel markets are undergoing significant change. Having said all this we believe the poor share price performance and valuation largely reflect the fact these negatives are known by the market.
We have cut our earnings per share estimates by 6%-8% going forward, given the weakness in UK parcel as well as updated foreign exchange forecasts. Royal Mail trades on...a12.3 times PE versus peers on...and 7-16 times. However, we regard Royal Mail as more of a work in progress than the likes of Austrian Post, bpost, and Deutsche Post.
Among the mid-caps, events company UBM has dropped 24p to 559p after it said it would buy US trade show organiser Advanstar Communications for $972m, funded by a £563m ($912m) cash call.
Recently Panmure Gordon suggested UBM should sell its PRNewswire business and seek acquisitions in the events sector.
