5) Twitter rejects $500 million offer from Facebook (2008) In 2008, Twitter’s popularity was on the rise, and Facebook quickly jumped at the chance to buy the company. Twitter rejected the offer for a couple of reasons. First, Facebook’s offer was an all-stock offer, and Twitter wanted cash. Twitter believed Facebook’s valuation was inflated, meaning the stock was far less valuable than Facebook claimed. Second, Twitter had high hopes for a secret revenue model that they hoped to launch in 2009. This month, Twitter finally went public. The company, which set its IPO pricing at $26 per share, saw its share price soar to $45.10 because of strong investor demand. The company received a valuation of over $24 billion.

Not too shabby.

I think the lesson here is if your product is a meme, SELL.

Twitter is a meme and they should not have sold. 

Instagram is a meme and they should not have sold. 

I don't think twitter is a meme... I look at it as more of a platform (and as we've all discussed before, they're missing out on the power that could bring).. Also I disagree w/ that Instagram shouldn't have sold.  It won't be but a few years max before the kids move on completely. They could've held out and gotten a larger price, but new apps will come along to push it out of the limelight.