They are one of the most well-known power couples in Silicon Valley. Slack, a messaging service that revolutionized office collaboration and was purchased by Salesforce in July 2021 for $27.7 billion, was co-founded by him. She is the co-founder and CEO of Away, a producer and retailer of fashionable baggage that received a $1.4 billion valuation in a fundraising round in 2019.

Stewart Butterfield and Jen Rubio are now gaining a reputation as trophy home collectors outside of Silicon Valley circles. The pair has amassed a real estate portfolio over the past two years that rivals that of some of the county’s most active billionaire house purchasers. Between January 2021 and August 2022, they went on a spending binge that resulted in the acquisition of at least five expensive residences, spanning at least three states and included two Manhattan properties, a Hamptons estate, a mountain property in Aspen, and a Taddeo Ando-designed ranch in New Mexico. They have invested at least $140 million since January 2021.

Requests for comment from Mr. Butterfield and Ms. Rubio went unanswered, but real estate experts said their homes are among the most opulent in their areas and showcase a variety of architectural styles. In 2009, Mr. Butterfield established Slack. Once Slack was acquired by Salesforce, he continued to serve as its CEO, but he completely exited the organization in early 2023. Away was co-founded in 2015 by Ms. Rubio. After Mr. Butterfield made a joking Twitter proposal the year before, the couple were married in 2020. They have two small kids together. Ms. Rubio referred to their household as a “dual-founder household” on Twitter in 2021. According to sources with knowledge of the matter, Mr. Butterfield and Ms. Rubio acquired an extensive New Mexico ranch from fashion designer Tom Ford in January 2021. Market insiders claimed that the final price was in the $40 million range, substantially lower than the $75 million the property had requested for when it first went on the market in 2016. The closing price wasn’t made public because New Mexico is a nondisclosure state. The roughly 20,000-acre Cerro Pelon Ranch, near Santa Fe, features Silverado Movie Town, an Old West whistle stop built in the 1980s as a shooting location for the film “Silverado,” starring Kevin Costner, Danny Glover, and Kevin Kline, as well as a main house and horse facility that were both designed by Pritzker Prize-winning architect Taddeo Ando. Later, Silverado Cinema Town appeared in “Thor” and “All the Beautiful Horses.” The main home is built of concrete in the customary manner of Mr. Andao, and it is situated over a reflecting pool. Also, there are two exclusive guesthouses and four distinct staff quarters on the site.

The ranch served as a haven for Mr. Ford, he claimed in a 2009 interview with The Wall Street Journal. “We reside in a synthetic environment. In the fashion industry, you constantly look forward to the upcoming collection. But when I’m at my ranch in New Mexico, with the sun shining down on me and rattlesnakes hiding in the bushes, I learn to appreciate the moment,” he remarked. New Mexico is home to many magnificent ranches, but this one stands out as the best, according to listing agent Kevin Bobrovsky. As far as the eye can see, there are no other buildings visible from where you are seated in the high desert. And it nearly feels like you’re in a boat while you’re floating on a reflecting pool.

Although Mr. Bobrovsky declined to comment on the buyers or the final price, he did mention that the property had received interest from outside. He said, “From Europe, Russia, all around the world. Together with neighborhood agent Neil Lyon of Sotheby’s International Realty, Clayton Arrigo of Compass represented the buyer.