Fonterra's listed Fonterra Shareholder Fund (FSF) units touched their lowest point yesterday, trading briefly at $4.99.
Following a rally after a low of $5.10 in mid April, the units climbed to $5.35 a week later, but in the following weeks have declined to $5 and briefly touched $4.99 yesterday.
At $5 the units are 38% down on their $8.09 high, two years ago.
The units are based on Fonterra's branded product sales, as opposed to farm-gate milk production, and are the only tradeable dairy-linked shares available to the general public.
The Reserve Bank this week reiterated its rising concern about the debt in the dairy sector and ability of its most indebted farmers to service loans, in the face of a near 50% decline in global dairy prices.
The central bank believes global dairy prices are set to continue, for an extended period.
While the farm-gate payout has been slashed and FSF units are at all time lows, dairy farm prices have held steady and were up 10% during the past year.
Craigs Investment Partners broker Peter McIntyre said aside from the Reserve Bank's analysis, it was the ongoing questions around dairying driving the unit price down.
''There's been no real bottoming out of the GDT [Global Dairy Trade fortnightly auction prices] ... with an excess of supply from markets outside New Zealand,'' he said of US and European production, which is gathering pace at a time global demand is down.
There remained a combination of ''discontent'' about Fonterra's poorer-than-expected first-half result, plus comparisons to other companies, and the value of milk powder and skim milk.
He said some FSF unit sales could be linked to forthcoming end of the financial real.
''This [present unit price] raises the question of whether there will be another downgrade to the payout,'' Mr McIntyre said.
