An independent trader apparently intent on securing his place in market history was responsible for oil prices briefly touching the unprecedented level of $100 a barrel - on the back of a single tiny trade, writes Javier Blas.

Some observers questioned the validity of the price mark when it emerged that the peak was the result of a trader - one of the "locals" who trade on their own money - buying from a colleague just 1,000 barrels of crude, the minimum allowed, industry insiders said. He sold them back a short while later for a small loss. The deal on the floor of the New York Mercantile Exchange was at a hefty premium to prevailing prices.