Not all hedge funds are obligated to disclose their holdings, trades, or performance.
About half of them are, however, and their performance can be found online through Morningstar and other sources. This information may not be as detailed as you would like, and you may try other means.
Since the Dodd-Frank Act in 2010, more information about hedge funds is available to the public. This does not mean that all the information you seek will be readily available, however, and there are many hedge funds that do not make their information public.
For more substantial information, you may try writing to the hedge fund directly. For secretive hedge funds, you may find it impossible to obtain information. This can be a dangerous thing for investors, as we have seen in the past.
An infamous example that shows the high-level of secrecy is Bernard Madoff’s fund. Mr. Madoff was running a scheme where he would receive billions of dollars because investors thought he was managing a successful fund.
This fraud continued for over two decades as the fund was allowed to keep information concealed from regulators and its own investors. Dodd-Frank legislation has sought to remedy this situation.