These are shockingly bad times for big banks, especially when you consider that the overall economy is supposed to be fairly healthy. The latest example is Germany's Deutsche Bank:

Deutsche Bank Q1 'most challenging in several decades': CFO

(CNBC) - Deutsche Bank posted a 58 percent drop in net profit in the first quarter, to 236 million euros ($267 million) compared to the same period last year.

The group posted a revenue decline of 22 percent year-on-year to 8.1 billion euros which it said "reflected a challenging environment and the impact of strategic decisions to downsize and exit certain businesses."

In its core business, revenue dropped 15 percent in its corporate and investment banking division and 23 percent in its global markets unit. It said 2016 would be the "peak year for its restructuring efforts."

Shares of the bank rose 4 percent in early trade on Thursday and the bank's Chief Financial Officer Marcus Schenck told CNBC that there were highlights among the earnings.

"On the positive side, we made very good progress on implementing further steps on our journey, as in the focusing of the bank, we're exiting certain countries, we're exiting certain market positions and all of that is evidenced in a risk-weighted asset position that we have as per the end of the quarter."

Nonetheless, Schenck conceded that the first quarter had been one of the most difficult in the bank's recent history.

"I can't debate away that this has been one of the most challenging quarters over the last several decades," he said, "(But) we've seen the markets calm down a lot in March and April and the performance in those two last months is definitely better."

Schenck said he had no "crystal ball" to see if the rest of the year would pan out. "There is still a lot of uncertainty out there and there is the 'Brexit' question (the U.K. referendum on EU membership in June) and with China, it doesn't look like there's going to be a hard landing as some people had feared but still, things can go wrong."

In the fourth quarter, the bank posted a net loss of 2.1 billion euros and full-year net loss (and a record loss) of 6.8 billion euros in 2015.When that data was released in late January, the chief financial officer Marcus Schenck said he expected 2018 to the first "clean" year for the bank as the lender continued to struggle with writedowns, litigation charges and restructuring costs.

For an entity as big and supposedly diversified as Deutsche Bank to post not just a 58% drop in profits but a 22% decline in revenues is "challenging" indeed. And it draws the eye to the risks these guys have taken on via an over-the-counter derivatives book that is, well, surreal. The following chart originally appeared in a Zero Hedge article.

So the odds that whatever DB management is doing today will fix this mess are pretty slim. Especially if the environment of negative interest rates, zero inflation and slow growth remains in place, as it almost certainly will.

But horrendously badly managed banks are just the tip of the iceberg. Negative interest rates are a mortal threat to all kinds of other financial business models, including insurance companies:

Germany: Where Negative Rates Are Lethal

(Wall Street Journal) - German life insurers are caught in a pinch that could eventually threaten their survival. Regulators are forcing them to boost capital levels at the same time that low rates make it hard to make money with their investments.

The question is how long before the ride gets bumpy enough to shake out the weakest firms.

German regulators are so concerned about the impact of negative interest rates on the country's life insurers that they have said they can only be sure the sector is safe through 2018. Even today, half the industry would be short of capital without the help of special measures.

The trouble lies in the promises insurers made to policy holders years ago, when nobody would have guessed central banks around the world would send interest rates barreling toward zero, only to remain there for years on end and even break into negative territory.

The German life industry is particularly badly affected by very low or negative interest rates because companies have historically offered what now look like high levels of guaranteed returns over very long periods.

Some insurers need to earn a continuing investment yield of more than 5% to meet guarantees to their policy holders, a report from Germany's central bank found in 2014. In a world where 10-year German government bonds yield less than one-quarter of 1%, that looks very hard to achieve.

Falling interest rates also increase the size of the liabilities on insurers' balance sheets, which can reduce their capital if assets don't increase in valuation enough to match.

Large European insurers such as Allianz SE,AXA SA, Assicurazioni Generali SpA andMunich Re all have big German life businesses, but regulatory concerns are more immediately focused on smaller insurers mainly unknown outside of the country. German life insurers earned gross written premiums of €89.9 billion ($101.4 billion) in 2014, according to the most recent statistics from German financial regulator BaFin.

One thing insurers can't rely on is a respite on interest rates soon. The European Central Bank is struggling to boost inflation to its desired target, and one of its primary levers is to send interest rates lower. That leaves an open question as to where insurers can find investments with the right combination of yield and risk that will allow them to make good on their promises.

Think of what's happening in global finance as an environmental change like a drought or temperature shift -- that happens too quickly for the ecosystem to adapt. Not every organism dies immediately, but relationships and inter-dependencies are disrupted, killing some and impairing others. Then comes a mass die-off in which a wide range of species disappear.

That, in a nutshell, is what a negative rate world means for banks, insurance companies, money market funds, pension funds, retirees, small savers and pretty much everyone else who depends on substantial risk-free income. The elephants like Deutsche Bank will make a lot of noise when they fall, but for each giant there are hundreds of smaller entities adapted for a very different world and unable to live in this one.