Does Glencore's float mark the top of the commodities boom?

Giant commodities trader Glencore has confirmed that it's planning to list on the London and Hong Kong stock exchanges. The Swiss group hopes to sell up to $11bn of shares (most of it in London), with prices set to be announced in the middle of next month. It's set to be the biggest initial public offering (IPO) in the world this year – and the UK market's biggest ever. There's one glaringly obvious question that any contrarian investor will ask themselves when a big company like this decides to go public. Does this mark the top of the market?