An extremely rare and fully operational Nazi Enigma machine has sold for $365,000 in New York, setting a new record at auction. 
 
 
 
 The M4 machine, which was built between 1943 and 1945, is one of around 150 to have survived from an estimated 1,500 that were built as Nazi Germany fought to fend off the Allies. 
 
 A spokeswoman for Bonhams said the $365,000 sale price set a world record for an Enigma machine sold at auction. The purchaser at Wednesday’s sale was identified only as a private collector. 
 
 The M4, with four rotors, is the scarcest of all Enigma encryption machines and was used on naval submarines. 
 
 Its manufacture was ordered by German Admiral Karl Donitz due to concerns that the three-rotor Enigma machine had been compromised following the capture of a U-boat in August 1941. 
 
 The model was made rarer still by the sinking of 70% of German U-boats in the later stages of World War II, in part due to the breaking of the Enigma code, Bonhams said. 
 
 Of the 50 Enigma machines on display in museums around the world, only seven are M4s, taken from captured U-boats, the auction house said. 
 
 “The Enigma machine is an exceptional encryption device, one of the most sophisticated and complicated of its type,” said Bonhams specialist Tom Lamb. 
 
 Bonhams sold a fully operational M3 Enigma machine for $269,000 at auction in New York last April. 
 
 
 
 

 An exceptionally rare and fully-functional Nazi Enigma M4 enciphering machine used during the Second World War has sold for a whopping $365,000, setting a new world record at auction. 
 
 The item, sold yesterday at Bonham’s “Conflicts of the 20th Century” event, went to an unnamed private collector. At $365,000, it’s the single largest sum ever doled out for an Enigma machine. 
 
 
 
 The M4, named for its four rotors, represents the scarcest of the German Enigma machines. Manufactured during the latter stages of the war, only 150 still remain in existence from the 1,500 ever built. 
 
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 The M4 Enigma machines were used exclusively on Naval submarines. Back in 1941, after rightfully suspecting that the three-rotor Enigma machine had been compromised following the capture of U-570 in August, German Admiral Karl Doenitz ordered the construction of the four-rotor version. 
 
 
 
 After its unexpected introduction on February 2, 1942, the M4 played a major role in the Battle of the Atlantic. Codebreakers at Bletchley Park, who called it the Shark-key, worked frantically to break it. The M4 remained unbroken for almost a year before Allied forces were able to capture new codebooks. 
 
 
 
 The rarity of the M4 stems from the fact that around 70% of German U-boats were sunk in the later stages of the war—partly due to the breaking of the Enigma code. What’s more, captains were ordered to smash their machines when captured. Historians suspect that, for every ten M3s still in existence only one M4 remains. 
 
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 Currently, there are a total of 50 Enigma machines on display in various museums around the world. A mere seven of these are M4s, all of which were confiscated from captured U-boats. 
 
 
 
 [ Guardian | Bonhams ]
– The M4 is the rarest of the already rare Nazi Enigma machines, which could help explain why a working model just sold for a record $365,000 at an auction Wednesday in New York. The Guardian reports the 70-year-old encryption machine was purchased by an anonymous private collector. “The Enigma machine is an exceptional encryption device, one of the most sophisticated and complicated of its type,” a specialist at Bonhams auction house tells the Guardian. According to Gizmodo, the M4 was introduced in February 1942 and played a big part in the Battle of the Atlantic. It was called the Shark-key by US codebreakers and remained unbroken for nearly a year. Of the 50 Enigma machines currently in museums, only seven are M4s, the Guardian reports. The M4s were used exclusively on German U-boats, 70% of which sank toward the end of WWII, accounting for the machine's rarity. In addition, Nazi captains were told to break their Enigma machines when captured, according to Gizmodo.