Born in Fonditore di Montegallo, a locality in Ascoli Piceno also known as Santa Maria di Montegallo, Marc came from nobility and wealth, being the son of Claro de Rainaldo de Marchio. He began his studies in Ascoli, then continued at the universities of Perugia and Bologna, where he obtained his doctorate in law and medicine around the years 1444-45. After returning to Ascoli, he worked as a doctor for a while. In 1451, in order to respect his father's wishes, Marc married Chiara de Tibaldeschi. However, after the death of his father the following year, the couple separated by mutual agreement. They have their marriages annulled and renounce the comforts and privileges of their social condition, choosing to devote their lives to religion. They adopted the same habit, one joining the order of the Poor Clares at the convent of Santa Maria in Ascoli, and the other that of the observant Franciscans.
After undertaking his novitiate at the hermitage of Fabriano, Marc subsequently assumed the role of superior at San Severino, under the direction of Jacques de la Marche. The latter, alongside Bernardin of Siena and John of Capistran, is among the fervent defenders of evangelization and the fight against the Fraticelli. During the early years of his religious life, Marc also distinguished himself as a passionate preacher, leading the people in practices of devotion and penance.
Like the other observers, Marc de Montegallo actively engaged against the two major evils of his time: civil discord and usury. From 1458 to 1496, he made considerable efforts to promote peace and the common good in Ascoli, Camerino and Fabriano. His fight against usury is manifested in particular by the creation of the Mounts of Piety, also known as the Mounts of Christ or the Apostles.
According to hagiographical sources, in 1458 he founded the Mons mutuationis in Ascoli, a free credit institution, the functioning of which remains quite obscure. However, it is likely that Marc was aware of the existence of similar institutions in the city, and his early involvement probably aligns with what would become the central activity of his life: the promotion of the Pawnbrokers .
The following years of Marc de Montegallo's life remain quite vague, lacking reliable sources. It is possible that he stayed in Sansepolcro, Camerino, and Cingoli, places where institutions similar to that of Ascoli emerged. In 1470, Marc was in Fabriano, where a pawnshop was established in April, receiving the approval of the town's general council, the podestà, and "brother Marc de Monte de Sancta Maria in Gallo [...] in this same place of preaching". Fra Marco also contributed to the drafting of the statutes and the founding of this institution, designed as a completely free credit establishment, its operating costs having to be covered by specific income identified by the local authorities.
Between 1471 and 1486, Mark of Montegallo served as a preacher in Fano, Fermo, Ripatransone, Roccacontrada (present-day Arcevia), Ancona, and other towns in north-central Italy. During this period, he stimulated the creation, regulation, or reorganization of local pawnbrokers. In 1480, he was appointed tithe collector for the crusade against the Turks, an initiative launched by Pope Sixtus IV in response to the siege and conquest of Otranto.
Finally, he established the credit institution of Vicenza, whose statutes were approved in 1486. It was the first establishment of this type established in the territory of the Republic of Venice, a period marked by a particularly hostile climate towards the Jewish loan and the Jewish presence in general. This moment also coincides with the kidnapping of the Jews of Vicenza on June 12, 1486. Like the other Montes, the Monte di Vicenza is designed as a free service intended to financially support families in need, offering loans repayable over six months, capped at three deniers.
Marc de Montegallo had two small devotional treatises printed in Venice by Niccolò Balaguer: the Book of the Commandments of God from the Old Testament and the Tabula della salute. The first, specifically designed for reading in schools, stores and parishes, is part of the widespread production of texts in the vernacular aimed at prescribing the rules and behaviors necessary for the achievement of individual salvation for a lay public with rudiments elementary. The second belongs to the category of devotional and catechetical manuals intended to provide precise rules of moral conduct. Both works were then reprinted also in Florence. Around 1486, another composition by Marco was probably published, entitled Corona de la gloriosa Vergene Madre Maria, a devotional volume collecting prayers in honor of the Virgin, embellished with numerous woodcuts.
From 1486 to 1496, Brother Marc resided in Vicenza, in the convent of San Biagio Vecchio. During this period, he provided advice and leadership to the various religious communities of the city, as well as to the Franciscan tertiaries of San Marcello. In 1496 he returned to Vicenza, where he died on March 19 at the San Marcello hospital. His remains are buried in the church of San Biagio Vecchio. Initially moved in 1522 during the transfer of the brothers to San Biagio Nuovo, they were then moved again in 1797 to the church of San Giuliano, where they remained exposed to worship.