But investors are not sure how comfortable they feel about negative interest rates,

since the talk is of banks charging people to look after their money.

So are negative interest rates going to fade and die, or get deeper and wider?

With me to discuss this is Peter Westway, head of investment strategy at the Asset Manager Vanguard.

Peter, remind us why do we have negative interest rates at all.

Well, the reason we have negative interest rates is that central banks in some countries find it necessary to provide additional policy stimulus.

They start by cutting rates lower and lower. Then they hit zero.

At that point, they can either start printing money by doing quantitative easing.

Or now, they're starting to move rates into negative territories as well.

What do central banks want us to do?

Central banks affectively are trying to get us to spend more money because by doing that,

we increase economic activity in the economy in that pushes up inflation, which is what they want.

But is it really the case that people are going to be charged for,

these people to hold their money in their banks and investors are going to be charged for the privilege of lending to governments?

It's not quite the case. Not many banks are yet charging negative deposit rates.

And interestingly, as a result of that, that means that probably the pass through from these interest rates isn't getting through to the borrowing rates.

So, the effectiveness of these negative rates in encouraging people to spend more is probably a little bit diluted.

Ok, so let's look our first chart which tells us how prevalent negative interest rates are at the moment.

This shows that around 30% of the current issues out there for sovereign developed market bonds are in negative territory.

Now, that's a slight overestimate of how much governments are actually getting a good deal,

because of course some of those bonds were issued while rates were still positive.

And they've since moved into negative territory in the secondary market.

But even so, any government like Germany's, like Switzerland's going to the market now to raise money,

is getting a negative yield, which means in effect , we're paying them for the privilege of us giving the money.

Peter, why would investors want to invest in a negative yield?

Let's have a look at your second chart here.

Yeah, I mean, I think the really important point to remember here is why do you hold bonds in your portfolio in the first place?

And you're not holding bonds because they give you fantastic returns.

Equities are in your portfolio for that.

There's only two reasons. One, they provide you a bit of a dampness stability.

But second and most important, they provide diversification relative to equities.

So what this chart shows you is that if you take the worst quartile of stock market performance over the last 14 years, from 2001 to 2014.

So when equities fell 6%, this tells you how different duration bonds apply during those same periods.

And what you see is that typically, bonds would go up to counteract it.

So that diversification would still happen in negative interest rate world?

Yeah, I don't think, I mean I think a couple of years ago, we were beginning to think that this diversification had run out of road.

But what's still happening is that as interest rates are falling and falling, where we're seeing that there's almost no limit to it.

But the criticism of negative interest rates is being stepped up.

We've had Lowry Fynn of Blackrock saying people are going to have to save for longer. Is that correct?

Yeah, I think that basic point is correct. But I think it's mixing up too slightly different issues.

I think it's definitely the case that because we're moving into a low interest rate world,

investors are going to have to save more to earn the same income in their retirement as they would've done a few years ago.

Now that's partly being affected by the low interest rates and the negative interest rates that central banks are implementing at the moment.

But let's remember why central banks are doing that.

They're doing that in order to try and persuade people to bring consumption forward from the future to the present.

That's just a standard thing that policy makers do during a period when the economy is in a big downturn.

But even when this downturn is behind us, it's still gonna be the case that returns are going to be lower going forward

and people are going to have to save more.

So, poor old investors are really the people that are caught in the middle here between a bad long-run outcome and policy maker actions.

Just very quickly Peter, finally how long we're gonna have negative interest rates?

I think we're gonna probably have them for the next year or two.

Peter Westway, thank you very much indeed.

Thank you.