Is the yield curve inverted, and for how long?

How we count

• A curve day is a day with a published yield. Holidays and weekends have none.
• A spread is the 10-year yield minus a shorter yield, in basis points (hundredths of a percentage point). The yields have two decimals, so a spread is a whole number, and the spread is ours.
• Below zero is inverted. A spread of exactly zero is not.
• A spell is a stretch of curve days with the spread below zero in which a break of fewer than 20 curve days stays inside it. It ends after 20 curve days in a row at or above zero, and its last day is its last day below zero. The grouping is ours: another gap gives another number of spells. The longest unbroken run below zero is shown beside the longest spell.
• An era groups the spells of both spreads where each starts within 200 calendar days of the end of the one before. A spread's page lists the eras with a spell of 100 curve days or more.
• The yields from 2 January 1990 are Treasury's par yields. Before it they are the Board of Governors of the Federal Reserve System's Treasury constant maturity yields, which Treasury interpolates from its daily yield curve. The two are the same on every day both hold, and no day takes a value from both. How Treasury works out the yields has changed over the years.
• The counts are counts of days on which one yield was below another. The series of a shorter yield begins when it begins, and nothing is counted before it.
• On 9 December 1981, 10 December 2008, 18 December 2008, 24 December 2008 one of the two yields was not published, so the spread has no value those days. They neither break nor extend a spell.
• These are published yields and our counts of them, not a forecast, and not advice about any security.