Stabilization of multiple bonds through inductive effects
Since electron-withdrawing groups (EWGs) lower orbital energy (we can rationalise this in terms of reduced electron density leading to reduced shielding), they will stabilise multiple bonds - you see this in the Diels-Alder reaction, where EWGs on the dienophile reduce the energy of its LUMO and so accelerate the reaction by reducing the gap between the dienophile LUMO and diene HOMO (conversely, electron-donating groups on the diene destabilise its HOMO by the same logic and so also speed up the reaction).