伴随状语or同位语？

selene009

The loan company announced it would soon lend money to borrowers with proven records of their not paying back their loans on time, collectively known as the subprime lending market.
collectively known as the subprime lending market如果说做伴随状语也能说的通啊，但是答案是加了a group,变成a group collectively known as the subprime lending market.解释是做borrowers的同位语，这是为什么？