0509 GMT - U.S. Treasury borrowing needs remain substantial and, with bond auction sizes expected to remain steady into 2027, short-dated bills are likely to carry more of the burden, Columbia Threadneedle Investments' Gary Smith says in a note. "That choice buys flexibility today but creates rollover risk tomorrow," says the head of client portfolio management team in EMEA fixed income. Greater reliance on bills makes the funding structure more sensitive to short-term rates, investor demand and auction conditions, he adds. Debt-servicing costs and funding composition are becoming harder to ignore. The next quarterly refunding announcement on Nov. 4 should show how much further policymakers are prepared to take it, he says.