Investors are betting on higher inflation, and sending more cash than ever into the biggest exchange-traded fund that protects against rising consumer prices.

Signs that prices are starting to firm prompted investors to pile into the iShares TIPS ETF, which is comprised of Treasury Inflation-Protected Securities. Shares of the fund looked like a better bet last week, after the Labor Department reported that March consumer prices excluding food and energy rose by more than expected from last year, and oil prices held above $50 a barrel for 10 days straight.

“You can understand why somebody wants to come in and buy a little bit of inflation protection,” said David Keeble, head of fixed-income strategy with Credit Agricole CIB in New York. “With oil prices continuing to rise, albeit slowly, that should keep that momentum intact.”

The fund attracted $634 million last week, its biggest weekly inflow since it was created in late 2003.

Tumbling oil prices weighed down many measures of consumer prices earlier this year. Oil has rallied about 25 percent in the month ended Friday.

A market gauge known as the break-even rate, used as a proxy for inflation expectations over the life of five-year TIPS, last week touched the highest level October. The difference between yield on the security and fixed-rate Treasuries of similar maturity reach 1.7266 percent on April 17.

At the same time, Wall Street analysts don’t expect inflation to heat up any time soon. Consumer prices will increase by 2.2 percent in 2016, after a 0.2 percent rise this year, according to forecasts in Bloomberg surveys.

“It’s definitely not dead and buried,” Keeble said.