Private equity funds are subject to certain restrictions in buying stocks. In China, the investment operation of private equity funds is regulated by the Interim Measures for the Supervision and Administration of Private Equity Funds and other laws and regulations. According to relevant regulations, private equity funds need to comply with the following restrictions when purchasing stocks:

1. Investment ratio limit: According to relevant regulations, the investment ratio of private equity funds in stocks is limited. The specific restrictions vary according to the types and strategies of private equity funds. Under normal circumstances, the proportion of stock investment cannot exceed a certain proportion of the fund's net asset value.

2. Restrictions on investment targets: Private equity funds are also restricted by investment targets. According to relevant regulations, private equity funds cannot invest in enterprises and projects that do not meet the requirements of laws, regulations and supervision, such as industries or fields where investment is prohibited.

3. Investment term limit: Private equity funds also need to abide by certain investment term limits when buying stocks. According to relevant regulations, private equity funds generally need to hold shares for a certain period of time before they can be sold.

It should be noted that the above are general restrictions, and the specific restrictions should be determined according to the types, strategies and investment decisions of private equity funds. In addition, different countries and regions may have different restrictions on the purchase of stocks by private equity funds. If you have specific private investment problems, it is recommended to consult professional financial institutions or private fund managers.