Here is the latest Temasek annual report:
http://www.temasekreport.com/2010/documents/full_annual_report2010.pdf
On page 20, the Wealth Added is defined. On page 21, the Wealth Added for each year is tabulated (in billions):
2005: $7.2
2006: $15.6
2007: $23.4
2008: -$6.3
2009: -$68.1
2010: $41.8
Summing up the Wealth Added, we have Net Wealth Added since beginning of 2005 to be only $13.6 billion. Dividing by 6 years, this means $2.27 billion per year. This means less than 2% return per year since 2004.
We continue the analysis. The Wealth Added for each year for earlier years are (in billions):
2000: $19.2
2001: -$30.2
2002: -$10.0
2003: -$20.2
2004: $19.9
Summing up from 2000 to 2010, we have the Net Wealth Added since beginning of 2000 to be -$7.7 billion. That means we have a net loss in wealth measured from what we have at the beginning of 2000.
Why then does it seem that Temasek is making lots of profit? This will require deeper analysis. A wild guess would be capital injection, or what the report called "net capital received from our shareholder".
For example at the end of 2005, the total assets is $96.215 billion. To achieve the ending total assets at 2010 of $173.152 billion, the govt need to add in capital of about $14 billion per year. If the total asset size is increased in this way, then it is not due to the returns of the investment.
An analogy is this. Suppose you start with $5000 and then add in $1000 into your stock portfolio every year. After 10 years, if your portfolio becomes $16,000, then it is unfair for you to claim "my portfolio has grown from $5k to $16k over ten years". It is also unfair for you to continue "my portfolio has grown 12% per year". Although such statements are not technically wrong, they misled the reader into thinking that the growth is due to gains in the portfolio. Actually the net gain in the portfolio over ten years is only $1k.
Conclusion: Temasek is much less profitable than it seems. The statement that it has regained to its pre-crisis level is misleading. The claim that "Between March 2005 and March last year, Temasek's portfolio grew from $103 billion to $186 billion" need to be further qualified as to how much of the $83 billion increase is due to capital injection by the govt.