The chatter is unmistakable. From trading floors to investment committee meetings, "bubble" has officially entered the market dialogue. The latest Schwab survey reveals that 57% of professional traders now view the market as overvalued. Meanwhile, prominent economists are drawing comparisons to the dot-com era, with Apollo Global Management's chief economist Torsten Slok noting that today's top stocks are “more overvalued” then their counterparts were in the 1990s.