So what do we do with this information? Some prominent (and successful) investors -- Ken Fisher is one -- insist that one's portfolio should always track the sector diversification of its benchmark index, unless one has a specific reason for over- or underweighting.
If you're British, should you ponder poli-tics across the pond? Of course. The world is more correlated than you know - at half the world's market cap, the US has a powerful pull.