As Boeing (BA) offers yet another deal to its striking machinist union, the company is also fighting to avoid a credit downgrade. When it comes to the bond market, Boeing holds $53 billion in the S&P's U.S. Investment-Grade bond composite. Nick Kraemer with S&P Global Ratings says the economic fallout will depend on how it affects production. However, Nick expects the market to stomach a downgrade if it happens sooner than later.