Dubai-based oil rig supplier Shelf Drilling has cancelled its London initial public offer of shares in an unsurprising move given the lack of any messaging on subscription levels or price guidance during bookbuilding."This decision has been reached due to challenging public market conditions despite a positive response from prospective investors to the company, its strategy and operations," the company said in a regulatory statement. That does not entirely tally with recent issuance after more than $8.35 billion of $50 million-plus European IPOs priced last week, comprising 12 listings, including six priced by Shelf Drilling's joint global co-ordinators Goldman Sachs and Morgan Stanley.Bankers have warned in the past fortnight that the flow of issuance and patchy aftermarkets have led to investors becoming increasingly picky on IPOs and pricing. Certainly there is no belief that now is a difficult time to sell a new issue.Shelf's lead banks are running the Madrid IPO of Spanish logistics group Logista and the London listing of food concessions business SSP, which both opened books.In addition, Morgan Stanley is a global co-ordinator on ING's insurance arm NN Group, which priced, and Goldman Sachs is a global co-ordinator on the Milan IPO of drug maker Rottapharm, which began bookbuilding. One banker working on Shelf Drilling put part of the blame on weakness on the Dubai exchange, with the benchmark DFM General Index having lost almost a third of its value from its May peak. Yet this is largely driven by difficulties at construction group Arabtec and the collapse in its share price."What happened in Dubai was unfortunate," said the banker.