Inspired by the recent conjecture originated from graduated dark energy that Universe has recently transitioned anti-de Sitter vacua to de vacua, we extend $\Lambda$CDM model a cosmological constant ($\Lambda_{\rm s}$) switches sign at certain redshift $z_\dagger$, and call this $\Lambda_{\rm s}$CDM. We discuss construction theoretical features of find out that, when consistency s}$CDM with CMB...