So many investors are rushing online to buy Series I savings bonds and lock in a rate of 9.62% ahead of an October 28 deadline that a U.S. Treasury Department website selling the securities crashed.

The TreasuryDirect website is facing long delays as Americans race to buy U.S. Series I savings bonds before rates reset at the end of the month. One of this year’s best-performing investments, I ...

The Treasury’s website will undergo maintenance this weekend after record demand for series I inflation-linked savings bonds strained the system.

Inflation hedge Series I savings bonds paying 9.62% unleashed a flood of buyers to the Treasury Department website on Wednesday, crashing the website ahead of a Friday deadline to receive the ...