Investment banks have struggled in recent days to raise about $2bn of debt for Apollo Global Management’s buyout of Shutterfly, highlighting investors’ newfound caution toward the riskiest portions of the credit markets.

Barclays, Citigroup and other banks Apollo hired for the sale agreed to buy up to $280m of the financing themselves after failing to find enough outside investors, people familiar with the matter said. They also were forced to slash the price of the debt to entice investors to buy up the balance, which is expected to be fully sold today, they said.