The Carlyle Group and Apollo Global Management reported second-quarter results on July 29 showing that, while it is a sellers’ market for private equity holdings, the firms continue to face challenges making new investments.

For these firms, as well as rivals Blackstone Group and KKR, the conditions that have made the last couple of years a good time to sell assets-such as rising stock markets and renewed appetite at big companies for mergers and acquisitions-have presented obstacles to them as buyers. Elevated stocks have put the prices of many companies out of their reach, as has the robust appetite of corporate buyers, which are generally able to pay more for acquisitions.