In this video, as part of The Motley Fool's "Ask a Fool" series, health-care analyst David Williamson takes a question from a Fool reader, who asks:

Gilead Sciences (NASDAQ:GILD) seems to be on a down trend. Is there any specific reason, or should I just hold firm?

David Williamson owns shares of AbbVie. Follow David on Twitter: @MotleyDavid.

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