We cannot estimate the exact numbers, but just to put this point across, according to reports, a whopping 91% of many cyber-attacks on both small businesses and huge companies are deployed through spear-phishing emails each day. By and large, spear-phishing emails lead the pack when it comes to the most common cyber-attack vectors against businesses. 91% means that almost every company out there can fall prey to a spear-phishing attack each day.