One easy way to take New York’s temperature as its health gets sorted out is to follow the stocks that define it. We assembled the Observer 100 Index to watch the city wheeze and sing. Sadly, last week was atrocious: By Friday, despite unexpectedly nice news about unemployment, the Dow spent a good chunk of time below 10,000. Things were particularly ugly in Europe–where a few countries looked like they might slide into the ocean–but slightly better here. Click the slideshow to see the Observer 100 stocks that gained and lost the most over the week, and click here for the entries from weeks one, two, and three.