Harvard University’s failed bet that interest rates would rise cost the world’s richest school at least $500 million in payments to escape derivatives that backfired. Harvard paid $497.6 million to investment banks during the fiscal year ended June 30 to get out of $1.1 billion of interest-rate swaps intended to hedge variable-rate debt for capital projects, the school’s annual report said. The university in Cambridge, Massachusetts, said it also agreed to pay $425 million over 30 to 40 years to offset an additional $764 million in swaps.