Standard & Poor's dropped its rating on the Commonwealth of Puerto Rico to junk status on Tuesday, citing a reduced capacity to access liquidity to fund its operating deficit. The BB+ rating remains on negative watch. Even with a forthcoming planned debt issuance, the commonwealth «will remain constrained medium term», the rating agency said. S&P also dropped to BB the rating on the Government Development Bank of Puerto Rico, the island's appropriation-secured debt, and the Employee Retirement System debt. Nonetheless, S&P said the island is making progress in reducing its operating deficit. Puerto Rico has some $70 billion in municipal bonds outstanding, backed by a variety of revenue sources, which are widely held in muni bond funds because of their exemption from state, federal, and local taxes. A junk-rating may make it more expensive for the government to continue borrowing. Moody's Investors Service has its Baa3 rating of Puerto Rico on negative watch and Fitch Rating's has its BBB- rating on negative watch.