If Mario Draghi was hoping for a quiet countdown to his retirement from the European Central Bank, he'll be sorely disappointed. In fact, it looks as if the ECB president is intent on going out with a bang.

Mr Draghi will preside over his second last policy meeting (at which the ECB policy committee discusses rates among other things) this Thursday before handing the reins over to Christine Lagarde on November 1.

At his penultimate outing, Mr Draghi is widely expected to announce a stimulus programme with various policy moves.

"As the date draws closer (and the German economic data deteriorates) the market is becoming more convinced that major new stimulus is on the way," Paul Sommerville of Sommerville Advisory Markets said.

"The market certainly expects action." 

That action includes possible interest rate cuts.

Aren't interest rates already at zero? Can they actually cut them any further?

There are three main interest rates that the ECB sets. The rate on the marginal lending facility is the rate at which banks can borrow from the ECB overnight. It's set at 0.25% right now.

The rate on the main refinancing operations is the one that affects the interest rate that we pay on our mortgages, and, yes, it's set at zero right now.

As to whether they can cut that further, well, all you have to do is look at another rate set by the ECB - the overnight deposit rate.

This is the rate that banks get for lodging money at the ECB. It's already negative, at -0.4%. It's been there since 2016 having first gone negative in 2014. In other words, banks have been paying the ECB to put their money on deposit with them for the past three years. So negative rates are already here.

Which rate are they most likely to cut or could they cut all of them?

Theoretically, they could cut all of them, but the bulk of the attention has turned to the overnight deposit rate. This is the one that's already negative. The expectation is that they will cut it further by 10 basis points, or 0.1%, bringing it to -0.5%.

The rationale behind this move is that banks will be dissuaded from bolstering customer deposits and will instead look at ways of making it attractive to consumers to take out loans for houses, cars, home improvements, education etc.

So that would only affect the banks - it wouldn't really impact on the consumer, right?

Not necessarily so. Like every macro-economic move, it eventually has a knock-on impact downstream. The impact in this scenario is on the saver. People who have been lucky enough to have money to put aside in recent years have been getting a meagre to zero return on their deposits.

However, they should perhaps be grateful that the banks haven't been charging them for the privilege of minding their money. (European banks have started levying charges on big corporate clients for putting money on deposit).

These policies - while popular in countries with younger populations, where there tends to be a demand for credit for house buying etc - don't go down well in countries with older populations, such as Germany, where a large segment of the population is saving for retirement and finding it very difficult to build a nest egg without resorting to riskier investments, like stock markets.

This is why the German Central Bank has been staunchly opposed to the ECB's policies in recent years and continues to be so.

If they cut the main refinancing rate, could my bank end up paying me for my tracker?

Trackers are the one category of mortgage that automatically benefit when the ECB cuts the main 'refi' rate. However, trackers usually carry a margin of around 1% above the ECB rate. So while it is theoretically possible that the bank could be paying you for your mortgage, it's unlikely to happen in practice.

On saying that, it's not impossible and not unheard of either. A Danish bank recently started offering mortgages at a rate of -0.5% over ten years. Effectively, they're offering the mortgage holder the chance to pay back marginally less than they have been loaned by the bank.

As to whether variable rate mortgage holders would benefit in the event of a rate cut is at the discretion of an individual bank. Variable rates in Ireland are among the highest in Europe - partly due to the relatively high levels of both trackers and non-performing loans on the banks' balance sheets - but some recent competition in the sector has seen them come down to about 1% above the euro zone average.

Cutting rates is not the only instrument at the ECB's disposal. It could also indicate that it's keeping rates lower for longer.

Austin Hughes, chief economist with KBC Bank Ireland, says the regulator is expected to indicate that rates could remain at current levels or lower well beyond the currently indicated date of mid-2020.

"Financial markets currently see no material increase in ECB policy rates until 2023 and don't anticipate ECB rates will go meaningfully above zero for the foreseeable future," the economist said.

What else are they expected to do?

Among the other measures the ECB is expected to announce is a resumption of effectively boosting the money supply. In another time it would have amounted to the regulator printing billions of euro in additional cash to pump into the system, but what they do is notionally create billions of euro that they use to buy up the bonds of euro zone governments and some companies.

That should act to drive down the interest rate that governments pay on their debts thus making it attractive for them to borrow additional money to spend on infrastructure projects or other stimulus measures.

Is this what was called QE?

That's it exactly. QE, or quantitative easing, has been used with mixed results by major central banks all over the world since the financial crisis at the end of the last decade. Some argue that it gave economies the impetus to make back lost ground in the years after the global downturn.

Others argue that it just gave equity traders access to cheap money that's kept stock markets sailing towards successive all time highs in recent years.

The ECB deployed its QE programme between 2015 and the end of 2018. In all it spent €2.6 trillion buying up mainly the bonds of member states at a rate of between €15 billion and €80 billion a month. That works out at a spend of €1.3m a minute!

90% of economists polled by Reuters expect the ECB to announce a return to QE, starting with asset purchases of €30 billion from October. There could also be changes to the rules around bond buying given the dearth of eligible debt at the moment.

One area they could target is to increase the proportion a country's debt that the ECB can hold. Currently, that's limited to 33%.

Why are they doing all this? Did it not work the last time?

The jury is out as to whether or not QE was successful the last time. Since it entered recession in 2012, the euro zone economy has slowly recovered. Analysts were generally surprised at the pace of recovery in 2017 and the policy was widely deemed to have been a success.

However, since then, the global economy has shown signs of slowdown against the backdrop of burgeoning trade wars and slowing manufacturing output, particularly in the world's second biggest economy - China - and the euro zone's biggest economy, Germany.

Stefan Gerlach, a former Deputy Governor of the Central Bank and now chief economist with EFG Bank, said it wasn't clear if the manufacturing downturn would extend to the rest of the economy.

"If anything, the global economic slowdown and the approach of the 2020 US presidential election will increase the likelihood of the Sino-American trade conflict being resolved," he wrote in an opinion piece for the Project Syndicate.

He argued that now was not the time for the ECB to relaunch its bond buying programme.

"The euro zone economy is in much better shape than it was in March 2015, when the ECB introduced QE. Compared to then, the euro zone composite purchasing managers' index, a key indicator of business activity, is a little higher. Headline and core inflation are also higher, as are households' inflation expectations and the European Commission's economic sentiment indicator.

"Given such data, it is difficult to make a persuasive case for QE."

However, in response, the ECB is likely to point to inflation. The primary objective of central banks is to keep the rate of inflation close to, but not above, 2%.

In 2017 and 2018, as the most recent QE programme was winding down, inflation moved close to the 2% target. The most recent figures for August pointed to inflation falling to 1%, its lowest level since 2016.

Paul Sommerville says there may be some changes forthcoming in relation to inflation targeting.

"Some type of statement that the ECB would be OK with an inflation target above 2% for a lengthy period before curtailing stimulus," he suggested.

"This means that they may state that because inflation has been below target for so long, they would tolerate it running above target for some time before doing anything to stop it."

Is all this likely to work?

The ultimate measure of the success of these policies will be in the performance of the euro zone economy in the long run. If the economy tips into recession, will they respond with even deeper rate cuts or further stimulus measures?

This prompts the question as to where it all would end.

In normal circumstances, following a round of rate cuts and stimulus, a central bank would have started to increase interest rates again and brought them back to a sustainable level whereby they would be ready to lower again if an economic slowdown set in.

The problem for the ECB is that hasn't yet got back to that position meaning it's having to act from an already extraordinarily accommodative position, leading many to draw parallels with the situation in Japan, which has been battling low inflation and anaemic growth with stimulus measures since the 1990s.

The successive rounds of bond buying by various central banks around the world have had an impact on bond yields and, while that's a good position for the governments that are borrowing the money, it's not necessarily good for investors and pension funds who are buying the bonds and finding it difficult to get any return.

In fact, in some cases, it's costing them to hold the bonds. According to various measures, in excess of $15 trillion worth of bonds now carry negative interest rates.

There's also the effect on the euro. In the event of the Central Bank delivering on all of these expectations, the single currency would likely weaken, which wouldn't be a bad development for euro zone exporters, particularly those trading with the UK. They've had to contend with a volatile, and mostly weakened, pound in recent months and years.

However, there is also the risk that the pound might bounce higher after Mr Draghi speaks, as Peter O'Flanagan, Head of Trading with currency specialists Clear Treasury, points out.

"Draghi has talked a big game and the problem with that is the market has built up some lofty expectations of what easing the ECB will actually deliver."

"Markets do not want a rate cut alone and there have been wide and varying suggestions as to what additional measures will be announced. The risk is that the ECB does not do enough and we see the single currency bounce higher," he concluded.

Lots of risk and much at stake. Mario Draghi is no stranger to such circumstances. Could the man who brought us 'whatever it takes' to save save the euro manage to pull one more trick out of the hat before he exits stage left?

His final act is expected this Thursday.