Although he does not expect to be able to launch a takeover of BP any time soon, proceeds from sales have so far enabled him to buy 2,000 shares in the company.
Koselleck has been in the UK helping the campaign group Platform with their campaign to stop BP's 20-year relationship with the Tate and end oil sponsorship of the arts.
Platform claim BP is using the art gallery to gain social acceptance and that a high-profile brand like the Tate would have little difficulty finding alternative funding. The gallery refuses to disclose how much the sponsorship deal is worth but estimates suggest around £385,000. Ex-BP chief executive John Browne is also chair of the Tate's board of trustees.
Protestors from another campaign group Liberate Tate made their own protest in April this year when they entered Tate Britain and poured an oil-like liquid over a demonstrator.
Kosselleck says he himself was first motivated to take on BP as an artist more than 10 years ago when he witnessed oil spill on the beach while on holiday in the Netherlands.
'While building sandcastles together with my daughter, I came upon several pieces of a black, slippery, tar-like substance, which upon inspection, turned out to be washed up oil residues. These had the tendency to stick to one's feet, in particular between the toes, under the great heat of the summer sun. It was then that I decided, for ecological reasons, to collect this waste oil in a plastic bag,' he recalls.
His campaigning artwork has focused on BP as, in his own words, they were the 'ultimate greenwashing company'. And in 2010 he visited beaches in Missisippi, Alabama, Lousianna and Florida affected by the Gulf of Mexico oil spill.
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