This is the story of a tentatively recovering global economy possibly petering out.
Out over the horizon, for investors, stretch yields this low for many, many years to come.
For most, this is merely disappointing and pushes funds elsewhere for higher returns.
However, for the Accident Compensation Corporation, the steward of more than $40 billion in mainly conservatively managed funds to deliver the legislated insurance scheme's promises, a plunge in the value of bonds is a bit of a headache.
By law, ACC's future liabilities are always fully funded, using a 100-year timeframe and a discount rate set by reference to various key indicators that affect the long term value of the ACC's investment portfolio, set by the Treasury. In the March ACC accounts, the discount rate was 2.66 per cent.
There's a fair bet that will look high when ACC tables its accounts for the June 30 financial year, any day now. A discount rate around 1.8 per cent looks likely.
That 86 basis points difference may not look like much, but to the ACC it means almost certainly that it will deliver a whopping record Outstanding Claims Liability deficit.
This headache was already evident in the corporation's accounts for the nine months to March 31.
They showed ACC's OCL, its ultimate bottom line, almost as deep in deficit at $4.3b of unfunded liability as it was for its worst ever year, the GFC-affected 12 months to June 30, 2008. On that occasion, the OCL hit $4.77b.
Given the fall in global interest rates between March and June, this year's full-year deficit number could conceivably start with a seven, maybe even an eight.
There is no need to panic about this. A 100-year horizon means there's enough time to right the ship and a reasonable expectation based on past experience that there will be periods of over-shoot on the upside further down the track.
Meanwhile, MBIE, Treasury and ACC are beavering away on a regular review of the parameters for the scheme.
A record OCL deficit will require action of some sort and there are really only two choices: reduce coverage or raise levies. Both are political rather than ACC decisions.
They arrive in the lap of ACC Minister Iain Lees-Galloway, one of the Ardern Cabinet's more harried ministers, and Finance Minister Grant Robertson, who also needs more trouble like a hole in the head, right now.
With the Government still reeling from Labour's internal disaster and failing to gain much traction outside angering farmers, the last thing it wants is to gift National a 'raising taxes' Facebook ad if it agrees to a levy increase.
Pedants know that ACC levies are not strictly taxes, but no one else cares. Also, the Government made this dilemma worse by reducing or leaving levies unchanged earlier this year rather than accepting recommendations to increase Earners' Account and Motor Vehicle levies.
Just what accidents are covered is also highly politically charged.
For ministers in a compassionate government claiming massive investment in mental services to hold the line and back ACC's denial of coverage for psychological trauma experienced by the survivors of the March 15 mosque shootings shows what a costly can of worms lies down that path.
As the 2017 Briefing to Incoming Ministers from ACC observed: "A central policy consideration for the scheme is to ensure what it provides is financially sustainable.
"While individual changes to cover and entitlement can appear small in the short term, some changes can add up to create pressures on the scheme over time.
"MBIE is exploring a number of these issues e.g. working with the Ministry of Health", while the Treasury and ACC remain in close contact on the performance of its investment portfolio against the OLC requirements.
ACC is required by statute to make new funding recommendations every two years, with the next lot due next year: election year. A big OCL blow-out right now is not helpful.
