What have we learned over the past few days? There are the good surprises. Like the ones that come in a box with a ribbon, or a check from Taylor Swift to pay off your student loans. Or when your non-gifting husband gets you a Christmas present. Or a corporate earnings surprise to the upside. Happy happy. Then there are the other surprises. The kinds financial markets hate. While you weren’t working on Monday, an official Chinese crackdown on margin lending — which one strategist called a “nasty surprise” — triggered a nearly 8% rout for the Shanghai Composite (though it’s back up today). And we all know what ... (full story)