But in the discussion about Moody's surprise move last week to cut its rating for our biggest trading partner, there's one word that has been notably absent, even though it's a risk of growing importance to investors and officials. That word is "fintech".

Nowhere are the large potentially huge benefits of fintech - and longer-term risks - clearer than in China.

This realisation comes as financial regulators everywhere, including in Australia, start to turn their attention to how these risks could eventuate, if fintech one day grabs a larger share of the financial services market.

Fintech, short for financial technology, is one of the great buzzwords in finance today. It describes the wave of new digital businesses looking to cream off some of the profits made by banks, wealth managers, and insurers.

When it comes to lending, China's fintech sector is the biggest in the world by miles, as underlined in a report published last week.

The Bank for International Settlements looked at the size of fintech credit - lending over digital platforms such as peer-to-peer lenders - and how the sector might eventually impact financial stability, if it gets big enough.

It said China had an estimated US$100 billion in fintech-arranged loans at 2015, citing a study by researchers from groups including KPMG, University of Sydney, and University of Cambridge.

That's roughly three times the size of US fintech credit, 24 times bigger than the UK, and 361 times bigger than Australia's nascent fintech credit industry.

Much of this activity is "peer-to-peer" lending, where consumers bypass banks and lend their money directly to a customer via an online platform, typically as a substitute for a bank-issued personal loans, car loans or business loans.

Another illustration of China's fintech boom is the rapid growth in online investment platforms such as Yu'e Bao, a US$165 billion fund that this year became the world's biggest money market fund.

A Moody's presentation this month pointed to Yu'e Bao's growth as one example of how online finance is helping to fuel the boom in "shadow banking".

The explosion in online finance apps, and smart phone use, means households that were previously snubbed by banks, such as those on lower incomes, are being brought into the finance sector.

For less wealthy countries such as China, the potential economic benefits of such a fintech boom are significant.

International Monetary Fund chief Christine Lagarde this month said harnessing the power of fintech should be a key priority for China as it sets about a massive infrastructure splurge known as "One Belt, One Road". Lagarde cited IMF estimates that economies that can extend financial services to citizens, such as giving a small business owner a loan, will grow 2 to 3 percentage points faster.

But there are also risks with fintech, with which financial regulators are grappling.

Importantly, fintech credit is still tiny compared with traditional banking. Even in the massive Chinese market, the US$100 billion in fintech loans in 2015 was a fraction of US$652 billion in consumer loans from banks in the same year.

All the same, last week's report from the BIS, prepared for the powerful Financial Stability Board, outlined a number of risks and in fintech lending business models.

One is that greater use of algorithms to allocate loans could erode lending standards - a claim P2P lenders reject. The BIS said there is no way to know if the new breed of digital lenders may be riskier, because they haven't been tested by an economic downturn..

Marketplace lending may also be more "pro-cyclical" - deepening a downturn because investors will pull back on lending their money. It could also have a "disorderly" impact on banks if their profits are attacked by online upstarts.

To be fair, the report stressed that lending via fintech platforms is still tiny in most countries, and these risks would only occur if online lenders started to gain a "significantly larger" share of credit.

Even so, these are not just hypothetical risks. Online platforms are already having a real impact on China's financial system by adding to growth in its less-regulated "shadow banking" sector.

The Moody's credit downgrade of China's government explicitly acknowledged the country's shadow banks, whose share of Chinese credit have ballooned by more than 50 per cent in the last five years, accounting to 28.5 per cent of the country's financial assets. As the example of the fund Yu'e Bao shows, digital finance innovations are adding to the shadow banking debt splurge.

The RBA has also repeatedly raised its concerns about the risks posed by China's shadow banks. Last month's Financial Stability Review said shadow banks posed "significant risks" to the country's financial system, because they tend to write riskier loans, as well as relying on shorter-term funding.

These sorts of risks have prompted China's government to put the brakes on shadow banks in the past year, and introduce new rules for "internet finance".

It is probably too early to say how effective these actions have been, but as one of the most Sino-dependent economies in the world, it is in our interests for this particular crackdown to succeed.