Editor's Introduction: Green Investment Evolves And Matures

With energy prices low by recent standards, credit conditions stubbornly tight—by any standard—and cap-and-trade legislation on life support, you'd think green investment would be in the doldrums.

A decade, even five years ago, that might well be the case. Today, green has ingratiated its way into the economy, reaching wider and deeper than some realize.

Part of that success lies in the sector's powerful evolution and maturation. Though alternative energy and conservation still matter, energy efficiency and management are now at the fore. Green has a row on the balance sheet and the bottom line. Companies are buying the technologies or even the businesses to ride the wave of profitability.

The investment landscape reflects all of this, as does our latest special report, "Investing In Green."

Cleantech remains the top investment choice for venture capital and VC investment through the first three quarters of this year ($5.73 billion), surpassing all of 2009. And more of that money is going to latter-stage fundraising rounds, rather than startup.

And in the wake of the carbon market letdown, the smart money is also sizing up a group of smaller, but more evolved environmental micro markets, such as credits for watershed mitigation. acid-rain emissions and water rights, as well as renewable-energy and energy-efficiency certificates

Mergers and acquisitions are now a force in the space, as startups look for partners with deep pockets to grow their businesses or larger firms look for ways to acquire technology or entire businesses. Through September, 580 companies merged or were bought out in deals totaling about $27 billion. Partnerships are also becoming more common.

There's been a number of important cleantech IPOs, including automaker Tesla Motors

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[TSLA  Loading...      ()   ] and European sensor maker Sensata

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[ST  Loading...      ()   ], in what's been a rough market for any public offering. Still, some 64 companies went public, worth more than $5 billion.

In another development on the corporate front, companies are taking a bigger role in financing and deploying green technology , particularly in the areas of smart grids.

For retail investors, there's an expanding world of options, from single-company stocks to mutual funds to exchange traded funds, as well as green indices to track.

And with those ETFs, change may be afoot.

So, enjoy our special report, which we'll be featuring here in our green section and on the home page every day November 14-21,  part of NBC Universal's "Green Is Universal" campaign.