The Questor column at the Telegraph says it was wary of Glencore's shares when the mining and commodities trading house floated in London and Hong Kong in May. Questor thought there were likely to be better opportunities elsewhere that carried less risk. Three months on from their debut and Glencore shares appeared to bear out that wisdom - on Thursday closing around a quarter off their 530p May flotation price at 388.5p. So is now the time to get them cheap, after Glencore posted results broadly in line with consensus and even offered up some pleasant surprises? Questor sees it as one for institutional investors rather than retail and so, for now, sees no reason to change its "avoid" recommendation.IMI, which makes a range of sophisticated valves and controls that regulate the movement of fluids and gases, has an exposure to any number of industries and should serve as a useful bellwether for the world economy, says the Tempus team at the Times. The shares have understandably suffered in recent weeks, plunging from about £11 in late July to 785.5p before yesterday's 2.8 per cent bounce to 807.75p. IMI looks like a business well positioned for whatever is thrown at it. Most investment decisions today have to be based on where you think the global economy is going. If you are reasonably optimistic, the shares, on about 10 times' this year's earnings, look oversold, says the Times.The Investment Column at the Independent says that the insulation and roofing firm SIG operates in what can only be called tough markets. Construction activity remains relatively weak, and economic growth across its markets in Europe and the UK is looking increasingly questionable. In the UK, the Coalition is firm in its desire to take an axe to spending. This presents challenges for SIG, which draws around 6 per cent of its annual revenues from new building programmes in the UK public sector. We opted to hold in August last year. Since then, after rising and then falling sharply, the stock is back up, leaving us with a nice profit. We would bank that and wait for the headwinds - which are not of the company's making - to pass before buying again, suggests the Independent.Aggreko looks increasingly like some sort of implausible perpetual motion machine, according to the Tempus team at the Times. The company keeps investing in plant that provides temporary power generation. It keeps increasing profits on the back of this, and the shares keep rising. Aggreko's halfway figures, stripped of the effects of big sporting events such as the World Cup last year, which distort them, showed underlying revenues up 21 per cent to £637.2 million and trading profits up 17 per cent to £127.1 million. The dividend is up 10 per cent to 7.2p. This column has suggested before that Aggreko shares, on 21 times earnings, look up with events. They still do ? but further progress in the long term looks quite probable, suggests the Times.BCPlease note: Digital Look provides a round-up of news, tips and information that is impacting share prices and the market. Digital Look cannot take any responsibility for information provided by third parties. This is for your general information only as not intended to be relied upon by users in making an investment decision or any other decision. Please obtain a copy of the relevant publication and carry out your own research before considering acting on any of this information.