In terms of personal branding, I would say the alma mater has more impact than a past employer:

• reason: a branded university has better longevity, durability and sustainability. A branded past-employer may lose much of the brand value over a few decades esp. in technology and esp. online .. Sohu, Motorola, Merrill, Microsoft, SUN, Bell labs, HP-way, big-blue
• reason: degree is easily and routinely verified
• reason: a much larger number of individuals can put NYSE or GS on the resume after a very short work project. No differentiation between long-term, high-ranking employees vs short-term junior contractors

What types of personal branding would have even higher impact than the alma mater? Nobel prize. Gold medals. high-profile publications/inventions