New York--Online advertising company 24/7 Media Inc. said on Wednesday its fourth-quarter loss widened sharply and it warned of a 35% to 40% decline in revenue in the first quarter, compared with the fourth quarter. The company reported a pro forma loss of $31.7 million, or 75 cents per share, compared with a loss of nearly $13 million, or 58 cents a share, a year earlier. Revenue fell to $38.6 million for the quarter from $48.1 million in the third quarter and was nearly unchanged from $37.1 million in the fourth quarter of 1999. Network revenues, the bulk of its business, fell to nearly $22 million from $31.7 million a year earlier. However, the company said it has secured an equity credit line of up to $50 million over the next two years.