Goldman Sachs has a problem

Goldman Sachs has a problem.

The US bank beat earnings estimates on Tuesday, with a strong performance in equities trading, debt underwriting and asset management helping power the beat.

But the troublesome fixed income, currency and commodities client execution unit had a weak quarter, with revenues of $1.16 billion 40% lower than the second quarter of 2016, and down 31% from a weak first quarter. The bank put that down to "significantly lower net revenues in interest rate products, commodities, credit products and currencies, partially offset by higher net revenues in mortgages."

At $1.16 billion, FICC revenues were significantly lower than equities trading revenues, which came in at $1.9 billion. It's also the worst quarterly performance for FICC since the fourth quarter of 2015. Here's a breakdown of Goldman's FICC revenues in recent quarters:

• Q2 2017 - $1.16 billion
• Q1 2017 - $1.685 billion
• Q4 2016 - $2 billion
• Q3 2016 - $1.96 billion
• Q2 2016 - $1.93 billion
• Q1 2016 - $1.66 billion
• Q4 2015 - $1.12 billion

To be sure, the weakness in FICC was not unexpected. But the scale of the decline at Goldman Sachs is likely to worry Wall Street analysts and investors. Here's a comparison with what other Wall Street banks have reported so far:

• Goldman Sachs FICC revenue - $1.16 billion - down 40% year-on-year
• JPMorgan FICC revenue - $3.2 billion - down 19% year-on-year
• Citigroup FICC revenue - $3.4 billion - down 6% year-on-year
• Bank of America Merrill Lynch FICC revenue - $2.1 billion - down 14%

The weak second quarter performance also follows a tough first quarter, when revenue ticked up just 1% on the first quarter of 2016, and dropped from the final three months of 2016.

Goldman Sachs delivered $2.8 billion in FICC revenues in the first half, down 19% from the same period last year. For context, that figure was $4.7 billion in 2015, and $5.1 billion in 2014. It stood at more than $5.6 billion in 2013 and 2012. In 2011, it was $5.9 billion, and in 2010 it was a whopping $9.4 billion. Goldman Sachs' first half performance in FICC client execution is its worst since the US bank started reporting the results in the current format.

"A mixed operating environment persisted into the second quarter as conditions continued to support underwriting and M&A, while constraining certain market-making activity," Lloyd Blankfein, chairman and chief executive, said in a statement.

Expect Wall Street to want answers about that "mixed environment."

Get the latest Goldman Sachs stock price here.