Facebook's stock is down again despite a boost after Apple announced tighter integration with the social network on new mobile devices and Mac computers.
Shares of Facebook Inc. lost 10 cents, or 0.4 percent, to close at $27 on Monday.
The stock is down about 29 percent from its initial public offering price of $38. Since it started trading publicly on May 18, it has fallen on 10 trading days and risen on six.
Investors are concerned about Facebook's ability to keep increasing revenue and about how it will make money from its growing mobile audience. But many analysts hold upbeat long-term opinions.
On Monday, Apple Inc. said its new software will make it easier for users of Apple products to share content on Facebook and other social-media services.