* Megan McArdle: Tricky thing about income mobility

* Steven Davidoff: Lessons from Diamond’s Pringles fiasco

* Charlie Gasparino: Regs may expand definition of “insider trading”

* Morning Call: U.S. futures point lower, London falls early, European shares slide and the Nikkei retreats.

* Just a hat: Simplicity in innovation

* Surf’s up: TPG makes offer for Billabong

* MF Global reveal: You may be a bank counter-party

* John Carney: Does Germany want Greece to default?

* Why not? Linsanity reaches Quora

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* Eventbrite Q&A: How to marry your co-founder without killing your startup