Interpublic Group reported a sharp drop in quarterly earnings on Tuesday, the latest advertising giant undercut by the prolonged downturn in spending by clients.

Interpublic, which counts General Motors as one of its single largest clients, posted second-quarter earnings of $20.9 million, or 4 cents a share, down from $88.1 million, or 17 cents a share, a year earlier.

Revenue fell 19.7 percent to $1.47 billion, the parent company of well-known agencies like DraftFCB and McCann-Erickson said in a statement.

Interpublic reported a 14.5 percent drop in organic revenue, a closely watched industry benchmark that excludes the impact of foreign currency and recent acquisitions. It said part of that drop was due to declines in spending from the auto sector and on events marketing.

(Reporting by Paul Thomasch; Editing by Lisa Von Ahn)

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