Two conducting spheres of different radii each have charge -Q. What occurs when the two spheres are connected with a conducting wire?

Two conducting spheres of different radii each have charge -Q. What occurs when the two spheres are connected with a conducting wire?I was told that the answer is negative charge flows from the smaller sphere to the larger sphere until the electric potential of each sphere is the same, but I don't understand why. If they are both negative charged, wouldn't they just repel each other, or does the area matters.