Bloomberg noted in an article that rising bond yields are typically indicators of stronger economic growth and higher profits for banks. That might not be the case this time, as a 30-year bull market in U.S. government debt shows signs of coming to an end.

Bloomberg said that banks have bought bonds, whose prices decline as interest rates rise, because they’ve had trouble finding borrowers. Bloomberg notes, according to FDIC data, securities made up about 21% of the assets at U.S. lenders at the end of March. The figure has been above 20% since the three months ending September 2010. Prior to that, the 20% level was last crossed in 2004.

Bloomberg quoted an analyst at FBR Capital Markets as saying, “Higher rates without meaningful economic growth are bad for banks. A lot of these banks have put on big securities portfolios at very low rates, trying to put their money to work. If rates move up materially, those things will be marked down.”

To read the Bloomberg story click here.