has closed  on a new $438.8 million fund intended to finance young biotechnology and cleantech portfolio companies. This is the sixth seed and early-stage fund the London-based firm has raised. Perhaps best know for its prescient investments in technologies like Skype, MySQL (sold to Sun Microsystems for $1 billion) and Betfair, Index has been relatively insulated from the economic downturn, and is looking to expand its reach in the health care and green sectors.

Despite this stated goal, Index’s most salient investments in the last year were mostly in technology and web-based service companies, including French recommendation software maker Criteo, social game network Playfish, British dating webcam site WooMe, and Israeli ancestry-tracker MyHeritage. The exception was French pharmaceutical company NormOxys, maker of a small-molecule compound capable of increasing oxygen content in the bloodstream — a possible treatment for cancer, anemia, stroke, diabetes, cardiovascular disease and Alzheimer’s. Yet no cleantech company made the list. In fact, looking at Index’s full portolio, its hard to pull out even a handful of green ventures.

This may change soon with the new funds, provided by existing (yet undisclosed) limited partners. While no plans have been released, green technology is an increasingly hot ticket, proving to be fairly recession-proof and heavily supported by the government. When it comes to lifescience opportunities, Index told VentureWire that it is on the lookout for companies with robust product pipelines and more mature companies that have proven their marketability. It also plans to place more emphasis on drugs addressing cancer, immunology, inflammation and problems affecting the central nervous system.

Regardless of what it chooses to fund, Index says it plans to make long-term investments in the near future. The fund, Index Ventures V (the roman numeral doesnt include the small pilot fund prior to Index Ventures I), is expected to last for about a decade, allowing the firm to back its portfolio companies for three to seven years — oftentimes, the full duration of early stage development. Accordingly, the firm says that it is on the lookout for less-risky companies with strong cash flows that may need a little help over the next several years to get by before taking off when the economy bounces back.

Index Ventures closed the same amount for its previous fund in February 2007. It currently has offices in Geneva, London and Jersey. Also among its galaxy of stars are social radio platform Last.fm, concert recommendation service SongKick and online video site Joost.