Think NIRP is only allowed in select European countries. Moments ago the US Treasury sold a whopping for the series $14 billion in TIPS. The yield? A record low -1.286%, courtesy of TIPS being the only US debt instrument allowed to price at a negative yield (but not for long: JPM's new head of the London CIO divison Matt Zames who is also head of the TBAC is working hard at getting negative yields legalized across the board). The first time the Treasury sold TIPS at a negative rate was back in 2010, when it priced $11 billion at -0.55%. The comment back then: "It signals people’s expectation of the Fed being able to create some inflation with the QE program,” said Alex Li, an interest-rate strategist in New York at Deutsche Bank AG, which as a primary dealer is required to bid at Treasury auctions. “With nominal rates so low, in order have high TIPS breakevens you’ve got to have negative real yields on the five-year." It didn't then. It won't now. Of course, if the CPI were actually adjusted to reflect reality, then TIPS would be the best investment imaginable. As it stands right now, it will likely keep losing money until such time as the CTRL and P keys are finally superglued in the on position.
From the Treasury:
and a chart of 5 year TIPS yields courtesy of John Lohman: