10-year and 30-year Treasury auctions: tails, bid-to-cover and ZN order flow

How an auction works

Treasury announces each auction a few days in advance with its size. Bidders submit competitive bids, specifying a yield, or non-competitive bids, which accept whatever yield the auction sets. The Treasury accepts competitive bids from the lowest yield upward until the offering is filled; the highest accepted yield, the high yield, applies to everyone.

Before the auction, the security trades on a when-issued basis. The difference between the auction's high yield and the when-issued yield at the 1:00 p.m. deadline is what the market reads first.

The auction metrics

Why futures react

A tail means the Treasury had to offer a higher yield than the market was pricing to sell the whole issue; the new bonds come at a lower price, and nearby futures usually adjust in the same direction. A stop-through means the opposite. The size matters relative to recent auctions of the same maturity. Because long-term yields feed the discount rate for equities and mortgage rates, a weak long-bond auction can move index futures too, especially when the market is focused on government borrowing and term premium.

Order flow at 1:00 p.m. ET

In Treasury futures, the minutes before the deadline often see positioning into the auction, sometimes described as a concession, followed by a pause as bids are submitted. When results come out, the book can thin for a few seconds and the first trades sweep the inside levels. The footprint then shows whether the reaction extends or is absorbed as participants weigh the details of the allocation.

Reading ZN or ZB next to ES on the same timeline shows whether a weak or strong auction spilled into equities. A sharp rates move with an unchanged equity tape describes a technical auction result; a joint move describes a change in how the market prices rates.

In Senzoukria

Auction rows appear in the News calendar under US; names such as 10-y Bond Auction are described as “Debt auction — yield + funding signal.” and the Quant mode card classifies them in the Debt and budget family. The ZN / ZB preset of the news wire is described as “Fed, CPI, jobs, Treasury auctions.”

The DOM ladder next to the ZN footprint shows resting size per level, cumulative depth and session memory of prices that left the book, which makes the pre-deadline thinning visible level by level on Rithmic, NinjaTrader or Quantower sources.