I have been trying to pin down what makes me uneasy about Groupon, the online coupon business that has just been valued at $6.4bn in its latest round of funding, which involves raising $950m in cash.

Actually, I think the reason is right there – that Groupon has been carelessly described as a social media business like Facebook and Twitter but at its heart, it is a sales-intensive local advertising operation that is costly to build. Read more