Lopez established himself as a shopkeeper in Newport shortly after his arrival. By 1755 he was buying and selling goods throughout Rhode Island and dealing with agents in
Boston and
New York. One of Lopez's early business interests was the trade in
spermaceti, a wax extracted from
whale oil used in candle production. Lopez built a candle-making factory in Newport in 1756. By 1760, a dozen competitors had built similar plants in
New England.
Whalers could not supply the factories with enough spermaceti to meet demand, and the price of whale oil increased. In 1761, Lopez joined eight other merchants to form a
trust to control the cost and distribution of whale oil. Lopez expanded his trade beyond the North American coastline and by 1757 had major interests in the West Indian trade, which was closely connected to plantation economies dependent on enslaved labor. He also sent ships to
Europe and the
Canary Islands. Between 1761 and 1774, Lopez participated in the
Atlantic slave trade as a financier and merchant investor. Historian Eli Faber determined that Lopez underwrote 21
slave ships during a period in which Newport sent a total of 347 slave ships to Africa. These voyages formed part of the triangular trade system, in which vessels carried goods from New England to the West African coast, where they were exchanged for captive Africans, who were then transported across the Atlantic in the
Middle Passage and sold into slavery in the Caribbean and the Americas. According to historical studies of the Middle Passage, enslaved Africans were typically confined in overcrowded ship holds for voyages lasting several weeks to months, with mortality rates on many voyages reaching 10–20 percent due to disease, malnutrition, and conditions aboard ship. By underwriting such voyages, Lopez provided capital, supplies, and commercial backing that enabled these operations to take place. By the beginning of the
American Revolution, Lopez owned or controlled 30 vessels engaged in European and West Indian trade and in whale fisheries. By the early 1770s, Lopez had become the wealthiest person in Newport; his tax assessment was twice that of any other resident. His success was attributed to the breadth of his commercial activities, which included the manufacture of spermaceti candles, ships, barrels, rum, and chocolate, as well as investments in textiles, clothing, shoes, hats, and bottles. These enterprises operated within an Atlantic trading system that included and profited from enslaved labor and slave-produced commodities such as sugar and molasses.
Ezra Stiles, the
Congregational minister in Newport and future president of
Yale College, described Lopez as "a merchant of the first eminence" and wrote that the "extent of [his] commerce probably [was] surpassed by no merchant in America". In the mid-1770s, with growing tensions between
Britain and its
North American colonies, Lopez's fortunes began to decline. The
Continental Association enforced a boycott against trade with Britain. In October 1775, a
Royal Navy force anchored outside Newport's harbour and the population began to evacuate the city. In early 1776 Lopez relocated to
Portsmouth, Rhode Island, then to
Providence, Boston, and finally to
Leicester,
Massachusetts. Historian Marilyn Kaplan describes Lopez's losses during the American Revolution as "monumental." ==Philanthropy==