The Bank of New York Mellon (BK) reported a 26% decline in fourth-quarter earnings for the period ending Dec. 31 due to changing activity levels in the company’s depository receipts business and restructuring charges.

The bank reported earnings of $505 million, or 42 cents a share, for the period, compared to $679 million in income, or 54 cents a share, a year earlier.

Volatility from the mortgage market continued to impact the investment side of the bank’s business.

During the period, the company’s unrealized net of tax gain on its investment securities portfolio declined to $420 million from $461 million in September as values dropped on nonagency residential mortgage-backed securities.

For the entire 2011 fiscal year, net income remained relatively unchanged at $2.516 billion, or $2.03 per share. That compares to $2.518 billion, or $2.05 per share, a year earlier.

Total revenue for the year hit $3.54 billion, down from $3.751 billion in 2010. Investment services fees collected by the company hit $1.6 billion, down 8% from last year and 12% from the previous month. Both drops were driven by lower depository receipts revenue and higher money market fee waivers.

Write to Kerri Panchuk.