A record number of bottles of rare Scotch whisky were sold at auction in the first half of 2015 according to figures from analyst and broker Rare Whisky 101.
The first six months of the year saw 20,638 bottles of single malt go under the hammer, an increase of 35% on the first half of 2014.
The value of sales grew 33.8% to just over £4.6 million.
Rare Whisky 101 co-founder Andy Simpson said the trend by some leading brands to move away from age-statements on their current releases was generating more interest in older whiskies.
"Demand for rare whisky and the supply of bottles at auction are both accelerating at an extraordinary rate and this is driving up values," he said.
"Demand for desirable single malt Scotch brands and previously discontinued bottles remains exceptionally strong.
"The dead hand of marketing is gaining an ever tighter grip on the single malt category, where retail releases are becoming non-age stated and the number of bottles ever more prolific.
"The dearth of truly collectable releases over recent years has only fuelled demand for older and discontinued past releases where quality and rarity are powerful motivations for purchase.
"For many in the broader Scotch industry, export and sales figures appear challenging.
"However, the secondary market for rarities shows little of this stress.
"We see this as a clear future trend, with the value of scarcity increasing demand from connoisseurs, collectors and investors."
The top 100 performing bottles of investment grade Scotch increased in value by 8.9% in the first half and values have increased overall by over 500% since 2008.
Brora - which closed in 1983 - and Dalmore are the top ranked distilleries in the investment market, with Bowmore (up 13 places to number five) and Ardbeg (up 10 to nine), among the rising stars.
Interest in Japanese whisky is also on the up with values of Karuizawa up 66% on a year ago.