Earlier this week, I bought a Treasury bill.
Everybody calls Treasury bills T-bills, and they work like this: The government promises to pay holders of T-bills a specific amount on a specific day in the near future. For the T-bill I bought, the government promised to pay $1,000 on Oct. 31.
I bought the T-bill on Tuesday, before Congress had made the debt-ceiling deal, so it was unclear whether I would get paid back on time.
If people are worried about a bond, the price tends to fall.