James Saft is a Reuters columnist. The opinions expressed are his own.

If you are worried about the impact of a U.S. government shutdown on markets, you might just want to look past Treasuries and keep a weather eye on corporate bonds.

Investors will have good reason to dump U.S. corporate debt and shares in the event of a shutdown. Given that there are $29 trillion of corporate securities outstanding compared to only $9 trillion of Treasury debt in public hands some of those sales could flow into supposedly safer longer-term Treasuries even as corporate yields burst higher.

President Barack Obama proposed on Wednesday cutting the deficit by $4 trillion over 12 years, less than a week after Democrats and Republicans struck a last-minute stopgap deal to temporarily avert a government shutdown. Even so, the political divisions are deep and there are ample opportunities in coming months for impasse to lead on to nonpayment of bills, the sort of sort-of default that would doubtless send markets reeling.

“Markets will begin to anticipate a crisis,” said Rob Dugger, of Hanover Investment Group, a former partner in legendary hedge fund firm Tudor Investments.

“If government is forced into rapid adjustment it will be the private sector that gets hurt.”