Don't overlook Twitter's data. Twitter data from the last six months (Nov. 28, 2012 to May 28, 2013) for tweets containing the keyword "bubble" and other financial-market-related keywords.
Volume of “bubble”-related tweets
Month 1 (Nov/Dec) = 168
Month 2 (Dec/Jan) = 181
Month 3 (Jan/Feb) = 208
Month 4 (Feb/Mar) = 762
Month 5 (Mar/Apr) = 2,984
Month 6 (Apr/May) = 29,632
Even Cramer is concern about bubble now.
Sentiment: Strong Sell
Asian markets continue with Selling Spree overnight
Dow's triple digit loss at -216 points today. Has the bubble to the equity market begin?
We had housing bubble, junk bond bubble. This time is stock bubble.
Twitter's data indicate a lot of people concern about equity Bubble today