These are jubilant days for the U.S. stock market, which makes the decision last week by Superman—the cape-wearing superhero, not Fed chairman Ben Bernanke—to renounce his U.S. citizenship all the more perplexing. Is the Man of Steel worried about the dollar’s waning purchasing power, or feeling outshone by Bernanke’s herculean effort in lifting risky assets? Or has he been keeping his 401(k) plan in cash, instead of stocks?

The market was awash in records last week after Bernanke, our money-printer in-chief, signaled an end to the central bank’s Treasury-buying this June but promised to hold interest rates low well beyond that. As the dollar fell for eight straight days to a three-year low, the Russell 2000 index of small stocks joined mid-cap stocks at an all-time high, as did the Dow Jones Transportation Average. Large stocks climbed to three-year highs, while the Nasdaq Composite Index surpassed its 2007 credit-bubble peak to reach its highest close since December 2000.

By keeping their staffs lean and working everyone harder, U.S. companies kept their margins plump and managed to grow their profits much faster than the 1.8% pace by which the U.S. economy expanded in the first quarter. Ford (ticker: F) earned its biggest first-quarter take in 13 years, and profits jumped 36% at Chevron (CVX) and 69% at Exxon Mobil (XOM). Wall Street analysts, who hushed their bullish chorus when oil prices climbed and after the earthquake hit Japan, have resumed raising profit estimates. Over the past four weeks, they’ve raised their forecasts on 702 stocks within the Standard & Poor’s 1500 and cut just 473, says Bespoke Investment Group. That produces a net upgrade of 229, or 15.3% of the index—the most bullish in more than 10 weeks.

Economists seem just as hopeful. While many recently cut their estimates for first-quarter growth to 1.5% to 2%, most still expect U.S. economic growth to re-accelerate toward 3% or so in the second half. Main Street seems a lot less sure, with investors pulling roughly $6 billion from domestic mutual funds over the past two months (Source: Barrons Online).