Mr. Pressler, who fled Nazi Germany as a youth, was the anchor of a group that, with various lineups, performed all over the world for 53 years.Menahem Pressler, the celebrated pianist who fled Nazi Germany in 1939 and, after establishing himself in postwar America, co-founded the Beaux Arts Trio, which became the world’s reigning piano-violin-cello ensemble and dazzled audiences for a half-century, died on Saturday in London. He was 99. His death was announced by the Jacobs School of Music at Indiana University, where he had been on the faculty since 1955.At 14, Mr. Pressler hid on Kristallnacht, the night of broken glass, as Nazi thugs smashed his father’s shop. When World War II began in Europe, his Jewish family landed in Haifa, in what was then the British Mandate of Palestine. Traumatized, he nearly perished at 16, but he found the will to live in a haunting Beethoven sonata. In 1946, he won an international piano competition in San Francisco. A year later, he made his Carnegie Hall debut.After years as soloists, Mr. Pressler, the violinist Daniel Guilet and the cellist Bernard Greenhouse joined forces in 1955 and formed the Beaux Arts. Such groups, called piano trios although two of their members play string instruments, had been around for centuries. But theirs was a daring venture at a time when most listeners preferred string quartets, with their even sonorities and vast repertory, for intimate chamber concerts.There are technique and temperament issues in a piano trio. The elephantine grand piano can easily bully its smaller partners or timidly overcompensate. And the piano’s staccato notes have to blend with a smoother continuity of strings. Some trios are also notorious for two-against-one squabbles. But the Beaux Arts achieved what critics called a wondrous harmonic unity in a resilient three-way musical marriage.The final version of the Beaux Arts Trio in performance in New York in 2008, from left: Daniel Hope, Mr. Pressler and Antonio Meneses.Julien Jourdes for The New York Times“We do everything together, the good things and the bad,” Mr. Pressler told The New York Times in 1981. “We travel and get lost together. We eat meals together. As in every close relationship, the musical traits and qualities that first attracted us to one another can become irritants, so we have to keep renewing the attractions that first brought us together. We try to handle our separate egos and create a single ego for the whole group.”Over decades, the trio’s violinists and cellists came and went — changes that might have doomed the precarious balance of sound, interpretation and chemistry that is the heart of chamber music. But critics said the trio was held together by the diminutive, cherubic, irrepressibly ebullient Mr. Pressler, who as mentor and leader preserved its technical quality and its confluence of musical views.The Beaux Arts eventually won a devoted global following and many awards. It recorded nearly all the piano trio repertory — Mozart, Beethoven, Haydn, Schubert, Brahms, Dvorak, Saint-Saëns and others — mostly on the Philips label, through the boom years of LPs and into the digital age. The group was praised for redefining the perception of the piano trio and of chamber music itself.“In recent years, we’ve seen a rapid expansion not only of the audience for chamber music, but of that audience’s sophistication and its awareness that the genre also includes sonatas, piano trios, small vocal ensembles, quintets, sextets and indeed all manner of combinations,” John Rockwell of The Times wrote in 1979. “And for that expansion of awareness, we can partly thank the Beaux Arts Trio.”In 2008, when the Beaux Arts Trio disbanded after 53 years, Mr. Pressler was still its anchor, the last surviving original member. He was 84, but he continued performing as a soloist and with ensembles. He also continued teaching at Indiana University, where he held the Charles H. Webb chair in Music.Menahem Pressler was born in Magdeburg, Germany, on Dec. 16, 1923, 153 years after what is generally accepted as Beethoven’s birthday. One of three children of Moshe and Judith (Zavderer) Pressler, he began playing the piano at 6 and was an accomplished performer as a teenager, taught secretly by a church organist after Hitler’s persecution of the Jews rose to a fever pitch.He recalled Kristallnacht, in November 1938, when the Nazis orchestrated a nationwide attack on Jewish homes, businesses and synagogues.“The thugs broke into our family shop in Magdeburg — a gentleman’s outfitters,” Mr. Pressler told The Guardian in 2008. His English still accented with the German of his childhood, he slipped into the present tense as vivid memories returned: “We are hiding in the house, hoping it will go by. In the street, you hear running, yelling, smashing sounds, banging at the door.”Menahem, his parents and his siblings, Leo and Selma, escaped to Italy months later and then reached Haifa. His grandparents, aunts, uncles and cousins all perished in the Holocaust.Tormented by loss and dislocation and unable to eat, he grew thin and weak. One day, playing Beethoven’s Piano Sonata No. 31, he fainted. But it was a turning point.“It has idealism,” he said of the sonata. “It has hedonism, it has regret, it has something that builds like a fugue. And at the very end, something that is very rare in Beethoven’s last sonatas — it is triumphant. It says, ‘Yes, my life is worth living.’”He recovered, and at 16 he performed with the Israel Philharmonic Orchestra.After winning a Debussy competition in 1946, Mr. Pressler moved to New York. His Carnegie Hall debut, at which he performed Schumann’s Piano Concerto with Eugene Ormandy and the Philadelphia Orchestra, won rave reviews.“This, indeed, was the playing of a free artist, secure in his birthright,” Olin Downes wrote in The Times. “The presence of a huge orchestra, an authoritative conductor, an immense audience, did not and could not inhibit the warmth, the loveliness and certainty of his interpretation.”In 1949, he married Sara Scherchen. She died in 2014. His survivors include their son, Amittai; their daughter, Edna Pressler; and his partner since 2016, Annabelle Weidenfeld. Mr. Pressler had homes in London and Bloomington, Ind.In 1955, the same year Mr. Pressler began teaching at Indiana University, the Beaux Arts Trio made its debut at the Berkshire Music Festival in Lenox, Mass. (now the Tanglewood Music Festival).Touring was often a bizarre experience. Mr. Pressler played pianos that were out of tune, battered or broken. One piano’s pedals once fell off. In a town in Chile, he was presented with an upright. In another hall, the piano had a dead key, and a message: “I tried to fix that note but I couldn’t. Try not to use it too much.” Some page turners could not read music. The trio was stranded in India. Mr. Greenhouse did an entire European tour with his leg in a cast.But to perceptive audiences, the trio was a marvel, not only of sound but also of subtle sights. Its performers were in constant visual and aural communication with one another — heads swiveling and nodding, eyes making contact, bows signaling cues, the pianist’s left-hand upbeat cuing the cello’s entrance or the violin’s stroke: an undercurrent of almost imperceptible signs as the tidal melody swelled and ebbed.While the trio’s artistry was achieved over many years, it was tested periodically by the adaptations required to incorporate new members. After 32 years as the cellist, Mr. Greenhouse was succeeded by Peter Wiley (1987-98) and Antonio Meneses (1998-2008). Mr. Guilet was replaced by Isidore Cohen (1968-92), Ida Kavafian (1992-98) Young Uck Kim (1998-2002) and Daniel Hope (2002-8).The Beaux Arts often performed as many as 130 concerts a year in Europe, Asia, the Middle East and the Americas, including annual appearances at the Metropolitan Museum of Art and the Library of Congress.“Menahem Pressler: Artistry in Piano Teaching,” by William Brown, was published in 2008. That year, Mr. Pressler returned to Germany to observe the 70th anniversary of Kristallnacht. And in 2013, at 90, he made his debut with the Berlin Philharmonic, at a New Year’s Eve concert that was televised live throughout the world. More