Twitter has posted disappointing revenue of US$595 million for its first financial quarter. Analysts had expected $607.2 million.

Twitter is blaming marketers for not spending as quickly on ads as they had anticipated. It has forecast sales in the second quarter below analyst expectations.

For its first quarter, Twitter reported a loss of $79.7 million, while for the current quarter ending in July, it forecasts revenue in the range of $590 million to $610 million.

The results add mounting pressure on founder Jack Dorsey, reappointed CEO last year and who vowed to turn the business around. To back that vow, he restructured the board, replacing long-time members with new faces. He also made sweeping changes in engineering and product departments, and in October, he cut more than 300 jobs, or roughly 8 percent of the workforce.

Over the last year, Twitter’s stock has plunged about 65 percent. After this week’s earnings report, investors have sent the company’s shares down more than 12 percent.