This excerpt taken from the ELN 6-K filed Apr 11, 2005.
m Financial asset investments and impairment
Financial asset investments are stated at cost less provision for impairment in value. The carrying values of financial assets are assessed for impairment using established financial methodologies, including quoted market prices for quoted equity securities. Unquoted equity investments and non-traded securities of public entities are assessed using methodologies including the Black-Scholes option-pricing model, the valuation achieved in the most recent private placement by an investee, an assessment of the impact of general private equity market conditions, and discounted projected future cash flows. The factors affecting carrying values include both general financial market conditions for pharmaceutical and biotechnology companies and factors specific to a particular company.
Other financial current asset investments are accounted for on an amortised cost basis.