Image: Bolt of lightning at night over Somerset West, South Africa © Digital Vision,Getty Images

Nearly three weeks after Sandy hit the New York-New Jersey area, the tally of losses from the devastating storm keeps going up.

We now know the storm claimed more than 100 lives, along with thousands of homes and businesses. Estimates of property damage now range up to $90 billion, and that may still be low. Basic services like power have yet to be fully restored to all areas.

But it's not too early for investors and companies to start thinking about the impact of Sandy on the overall economy, sectors and stocks -- and the potential profits from the vast amount of work ahead. That's particularly true if we really are seeing an increase in extreme weather events, because these same companies stand to profit again and again.

So, with all due respect to those still suffering, including many of my fellow New Yorkers, here's a look at the potential winners and losers as we pick up the pieces after Sandy.

The macro view

Big picture, natural disasters typically tend to boost economic growth, because reconstruction adds more to the gross domestic product than the destruction of assets and net wealth takes away, concludes Credit Suisse global equity strategist Andrew Garthwaite, who has looked at the impact of several big disasters over the past decade.

So expect an initial dip in economic growth, followed by an increase above where the economy might have been without the rebuilding.

As for stocks, several kinds of companies obviously benefit from a big storm. And there's a big difference this time from past disasters.  

The big knock on "hurricane stocks" is that gains are one-off. But I doubt that's the right way to look at this anymore, for a simple reason. Given all fires, droughts, tornadoes and hurricanes we've seen in just the past couple of years, it seems pretty clear that because of climate change -- whatever the cause -- we're in a "new normal" for extreme weather.

Sandy was the second big hurricane to hit the New York City area in a year, following Irene. "We are now two-off, not one-off," says Stu Feldstein of SMR Research, a market-research firm in Hackettstown, N.J. "Things are looking pretty weird out there. Climate change could be for real."

New York Gov. Andrew Cuomo remarked that "we have a 100-year flood every two years now."

If you agree we now have a "new normal" for weather, there are two clear implications for investors. First, companies like Home Depot (HD) and Lowe's (LOW) get more of a rolling benefit than a one-off boost.

Second, utility companies and policymakers are going to realize at some point that we can't just keep repairing the damage caused by storms, only to do it over again in a year after the next one. Instead, it's time to rethink, redesign and harden our infrastructure against natural disasters. This could include installing storm surge barriers like those used around London, burying utility wires, installing better pumps in underground tunnels, and covering electrical components in the electricity grid and mass transit systems.

This suggests a steady stream of demand for construction-engineering companies and their suppliers, as a medium-term trend. The American Society of Civil Engineers already gives U.S. infrastructure a "D" grade. Sandy, in other words, really just exposed some big underlying spending needs. Even Washington's would-be budget cutters can't ignore this forever. (For another view, see Jim Jubak's "Rebuilding after Sandy? Maybe not.")

When looking for stocks that should profit from Hurricane Sandy-related rebuilding, I considered both of these big-picture trends, as well as the ongoing recovery in housing and the economic growth of emerging markets. Here are the companies and sectors poised to benefit.

Home Depot and Lowe's

When a natural disaster like Sandy strikes, homeowners flock to Home Depot and Lowe's to buy lumber, gutters and roofing materials, dehumidifiers, pumps, generators, cleaning supplies and more.

For both chains, sales at stores open more than a year, the golden metric in retail, jumped about a percentage point in the month following Irene, says Stifel Nicolaus analyst David Schick. A "new normal" of more extreme weather events will continue this trend.

But these two are not just natural-disaster plays. They benefit from other trends, too. One is the ongoing strength in housing, where the current recovery is no head fake, say many experts. "The housing market is looking pretty sound. I think it continues on," says SMR Research's Feldstein, who accurately called both the housing collapse and the ensuing rebound, ahead of most other analysts. "We have a gradual recovery taking place in both sales and home prices." This should continue to cap foreclosures, which have been declining steadily for several quarters, taking pressure off home prices.

"We believe the likelihood of an even more robust recovery has increased," says Morgan Stanley analyst David Gober. Morgan Stanley says home prices could increase 9% this year and 6% next year. This should help support home improvement sales growth of 5% to 6% in 2013 and 2014, says Gober.

Another trend helping Home Depot and Lowe's is ongoing consolidation. "The large, fragmented home-improvement market provides an opportunity for both companies to expand profitably well into the future," believes Morningstar analyst Peter Wahlstrom.

Richard England, the portfolio manager of the Calvert Equity (CSIEX) fund, prefers Lowe's because it's cheaper. Lowe's stock goes for 15.5 times next year's earnings, compared with 17.8 for Home Depot. Plus, Wall Street analysts haven't fully factored in ongoing merchandising improvements at Lowe's, believes England. This means Lowe's will earn more next year than analysts expect, he says, so its real forward price-earnings ratio now is more like 16.

In simple terms: Lowe's is even cheaper than it looks, relative to Home Depot.

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