The rupiah was at 9,200/9,210 to the dollar, compared with Wednesday's close of 9,190/9,200.
"Bank Mandiri was one of the triggers (behind the market's fall)," Kuo Capital analyst Mohammad Reza said.
He said technically, Bank Mandiri was poised for a correction some time ago, but investors only began selling after hearing speculation of a default in one of Bank Mandiri's bond investments.
Garment maker Great River International said last week that it was unable to pay the fifth coupon instalment within a two-week deadline extension on January 27. There is market talk that Bank Mandiri was among the bond's investors.
Great River issued 300 billion rupiah worth of bonds on which a 11 billion rupiah coupon payment fell due on January 13.
"It's old news but it affected sentiment on Mandiri," Reza said, adding the potential loss was small given Bank Mandiri's revenue size.
"Over the medium-term there should be an impact. The Fed's move will put pressure on Bank Indonesia to raise its interest rates considering January inflation was high and not to mention the (planned) fuel price hike," Reza said.
State-run Bank Mandiri was down 40 rupiah at 1,890 while Bank Rakyat Indonesia gained 25 rupiah to 2,850 and Bank Central Asia was up 50 rupiah at 2,975.
Index heavyweight Telkom was down 50 rupiah at 4,700 and Indosat down 200 rupiah at 5,550.
Cigarette firm Gudang Garam was flat at 17,400 and rival Sampoerna was up 100 at 7,600.