'Stock' was a U-boat wolfpack operation, in tandem with 'Grube', in the Arctic against the 'Golden' passage of the JW.62 convoy and a number of Soviet coastal feeder convoys (27 November/14 December 1944).
Unlike slightly earlier British undertakings to protect outbound and inbound Arctic convoys, the JW.62 convoy did not have battleship protection, a fact reflecting the 'Catechism' elimination of the German battleship Tirpitz as a threat. The JW.62 convoy of 30 laden ships and one rescue ship departed Loch Ewe with support furbished by the 8th and 20th Escort Groups (destroyers Keppel, Beagle, Bulldog and Westcott, sloops Cygnet, Lapwing and Lark, and corvettes Allington Castle, Bamborough Castle and Free Norwegian Eglantine and Tunsberg Castle being transferred to Murmansk).
The covering force comprised the light anti-aircraft cruiser Bellona, the 1st Division of the 7th Destroyer Flotilla (Caesar, Cassandra, Caprice and Cambrian) and the 17th Destroyer Flotilla (Onslow, Orwell, Obedient, Offa, Onslaught and Oribi), while further support was afforded by the more distant presence of the escort carriers Campania and Nairana together with the frigates Bahamas, Somaliland, Tavy and Tortola, and the Canadian 9th Escort Group with the frigates St John, Stormont, Monnow, Loch Alvie, Nene and Port Colborne.
On 27 November the convoy was located by German air reconnaissance and one of Nairana's fighters shot down the contact-keeper. The 'Stock' wolfpack (U-286, U-293, U-299, U-313, U-315, U-318, U-363, U-365, U-995 and U-992) and 'Grube' wolfpack (U-295, U-310, U-387, U-668, U-997, U-965 and U-1163) were deployed in the area to the west of Bjørnøya and to the north of the Kola inlet respectively. On 1 December the boats of the 'Stock' wolfpack were relocated to the Kola coast on the German assumption that the convoy had already transited the Bjørnøya Passage.
The convoy now detoured to the north as its support groups made an unsuccessful foray against the suspected U-boat concentration. Between 1 and 11 December several Soviet feeder and coastal convoys were attacked by U-boats. On 1 December the Soviet destroyers Derzkiy and Dostoinyi escorted the BK.40 convoy of five US ships from the White Sea to Murmansk, supported in the latter stages by the destroyers Uritskyi and Deyatelnyi. On 2 and 4 December U-363 unsuccessfully attacked the Soviet KP.17 coastal convoy of three ships on passage from Kirkenes to Kola escorted by four large and two small submarine chasers. On 3 December Oberleutnant Ernst-Ludwig Balduhn’s U-1163 sank the 433-ton coaster Revolutsiya of the KB.35 convoy, comprising two ships and two ex-trawler patrol boats, between Kola and the White Sea. On 4 December U-992 and U-995 made unsuccessful attacks on the Soviet KP.17 coastal convoy, which was being escorted by ex-US minesweepers, off the Kola inlet. On 4/5 December, in attacks on a Soviet coastal convoy in the entrance to the White Sea, U-997 missed. U-295 missed the destroyers Deyatelnyi and Zhivuchiy near Yokanga and was then counterattacked by the two Soviet warships. On 5 December Oberleutnant Hans-George Hess’s U-995 sank the 1,123-ton coaster Proletary of the PK.20 convoy, and Oberleutnant Diether Todenhagen’s U-365 sank the ex-US submarine chaser BO-230. On the next day U-318 attacked both the ships and the escorts of the incoming JW.62 convoy, the strength of whose escort had been boosted by the arrival of the Soviet destroyer leader Baku, destroyers Gremyashchiy, Razumnyi, Uritskyi, Deyatelnyi, Derzkiy, Doblestnyi and Zhivuchiy, and four submarine chasers: one of U2-93's torpedoes exploded in Deyatelnyi's wake. On 7 December Oberleutnant Hans Lehmann’s U-997 sank the ex-US submarine chaser BO-229, one of four such vessels constituting a Soviet anti-submarine group.
The JW.62 convoy entered port, without having suffered any losses, on 7 December. Before the RA.62 return convoy of 28 unladen ships and one rescue vessel, with the escort which had escorted the JW. 62 convoy, departed on 9 December, the Allied support groups and Kontr Admiral Vitali Fokin’s Soviet destroyer force (Baku, Gremyashchiy, Razumnyi, Derzkiy, Doblestnyi and Zhivuchiy) attempted to drive the U-boats away from the entrance of the Kola inlet. In the process, U-997 missed Zhivuchiy and Razumnyi on 9 December. Kapitänleutnant Rudolf Büchler’s U-387 was depth-charged and sunk by the corvette Bamborough Castle (or, according to the Soviets, after being rammed by Zhivuchiy) and only Todenhagen’s U-365 could establish contact with the convoy, making an unsuccessful attack on a tanker on 10 December and then, on the following day, torpedoing and damaging the destroyer Cassandra. Two days later this boat was still maintaining contact but was then sunk by a Fairey Swordfish anti-submarine aeroplane of Campania's No. 813 Squadron.