Rupert Murdoch's Sun on Sunday dipped below the 2m sales mark for the first time in December, with a month-on-month decline of just over 6%.
News International's Sunday edition of the Sun, which launched as a replacement for the News of the World on 26 February last year with publicity-fuelled sales of 3.22m, reported an average weekly sale of 1,886,739 in December.
This represents a fall of 6.1% month on month, some 122,543 copies, according to the latest Audit Bureau of Circulations figures published on Friday.
However, the Sun on Sunday remains the biggest UK Sunday title, ahead of the Mail on Sunday, which had an average circulation of 1,687,301 in December – down 2.60% month on month and 11.62% compared with December 2011.
The Sun on Sunday's percentage month-on-month sales fall for December is triple the rate of most rivals in the Sunday market, except for the Sunday People, which declined 3.86% compared with November.
December was the first full month of audited sales in which the Sun on Sunday has fallen below 2m, although in October the title dipped under that mark for the first time in sales on one weekend.
The last officially audited sales figure for the News of the World, which was closed last July was 2.77m.
The Sunday Telegraph proved to be the most resilient of the quality Sunday national titles, limiting its sales decline to just 0.98% month on month in December to 428,092. The year-on-year circulation decline at the Sunday Telegraph was 5.47%.
In December, the Independent on Sunday fared the next best with a month-on-month fall of 1.58% to 116,513, a 9.25% year-on-year decline.
The Observer, published like MediaGuardian by Guardian News & Media, fell by 2.26% month on month, to 230,833, a 13.44% year-on-year decline.
The Sun – Sunday edition
Headline circulation: 1,886,739
Month-on-month change: -6.1o%
Year-on-year change: n/a
Mail on Sunday
Headline circulation: 1,687,301
Month-on-month change: -2.60%
Year-on-year change: -11.62%
UK and Ireland paid-for circulation: 1,522,974 (90.3% of total)
Headline circulation: 1,024,543
Month-on-month change: -1.15%
Year-on-year change: -39.80%
Headline circulation: 473,336
Month-on-month change: -1.60%
Year-on-year change: -24.49%
Headline circulation: 428,406
Month-on-month change: -3.86%
Year-on-year change: -45.09%
Daily Star Sunday
Headline circulation: 360,747
Month-on-month change: -2.04%
Year-on-year change: -43.67%
Headline circulation: 877,482
Month-on-month change: -1.96%
Year-on-year change: -6.20%
Headline circulation: 428,092
Month-on-month change: -0.98%
Year-on-year change: -5.47%
Headline circulation: 230,833
Month-on-month change: -2.26%
Year-on-year change: -13.44%
Independent on Sunday
Headline circulation: 116,513
Month-on-month change: -1.58%
Year-on-year change: -9.25%
UK and Ireland paid-for circulation: 60,718 (52% of total)
Headline circulation includes lesser rate sales, subscriptions, bulks – copies sold to airlines, rail companies, hotels and gyms for a nominal fee and given free to the public – and distribution in Ireland and overseas. UK and Ireland paid-for circulation excludes bulks and overseas distribution; where this figure is not given, bulks and overseas distribution account for less than 5% of total circulation
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