Principal component analysis and factor analysis of term structure movements shows that between 80 and 90% of term structure shifts can be explained by a uniform shift that is roughly parallel. In contrast, our analysis of term structure data from 1986 to 2016 reveals that only 57% of the shifts have been uniform. Twist-and butterflytype shifts accounted for 28 and 10%, respectively, of all shifts. Remarkably, these frequency results are roughly the same for uniform and twist shifts determined on a daily, weekly, and monthly basis over the entire sample and over three subperiods. Based on historical data, an investor should expect a uniform shift in the term structure about 57% and a twist 28% of the time. Keywords Term structure shift • Spot rates • Principal component analysis JEL Classification G12 1 Macaulay (1938) originated the concept of duration. Bierwag et al. (1983) provided an excellent survey of the literature. 2 The prices on zero coupon bond, from which the returns were calculated, are based on spot rates implied by in prices of coupon bonds.