President Barack Obama has warned Wall St it should be "concerned" as talks to extend America's borrowing limit threaten to go to the wire.
"Democracy's messy. But when you have a situation in which a faction is willing potentially to default on US Government obligations, then we are in trouble," he told US television.
The US Government has been shut down for two days because of a political stand-off that economists fear will bleed into parallel talks about whether to extend America's US$16.7 trillion ($20.1 trillion) borrowing limit.
It is an annual negotiation that has gone up to the deadline three times since Obama came to power, and which stands to alter the course of America's economic recovery.
Wall St and Capitol Hill had been working on the assumption that the political circus would deliver the same result this year, but they are feeling less sure now that Congress has allowed the Government to shut down before resolving their stalemate.