  We present a summary of measurements sensitive to the CKM angle \phi 2
(\alpha), performed by the BaBar and the Belle experiments which both collect
B\bar{B} pairs produced at the \Upsilon(4S) resonance in asymmetric e+e-
collisions. We discuss the decays B -> \pi \pi, \rho\rho, a_1\pi and
(\rho\pi)^0. The CP asymmetries, branching fractions and polarizations obtained
are used to constrain \phi 2.
