Hernan Diaz, 50, was born in Buenos Aires and lives in Brooklyn. A finalist in 2018 for the Pulitzer prize in fiction with his debut In the Distance, which the New Yorker called “an offbeat western”, he is the joint winner of this year’s award – together with Barbara Kingsolver – for his second novel, Trust, out now in paperback. A slippery story of a Depression-era tycoon and his late wife as told four different ways, it made the longlist for last year’s Booker prize, whose judges called it “sly, sophisticated, insistently questioning [and] determined to rob us of every certainty”.

What led you to tell (and retell) the fictional life of a Wall Street financier?
Almost no novels in the American canon talk about money-making. Many American novels revolve around money, but the money’s already been made and the books are only about the adjacent symptoms bubbling up around money: the corseted manners of the wealthy and so on. Money has this almost transcendental place in American culture, yet it’s also taboo – we don’t talk about it and we don’t even understand it. That seemed bonkers and fascinating. On one hand, money resists narrative because it is coated in this rhetorical varnish of pseudo-science in order to be purposefully impenetrable. We’ve all had these experiences negotiating a loan or a credit card; like, it isn’t meant to be understood. But on the flipside, money is very reliant on storytelling: look at how desperately those who amass any kind of fortune try to account for how it was accumulated so they can present it in a legitimate way to the public.

Why did you avoid dialogue almost entirely in the novel’s first half?
The first section is written in this hyper-careful turn-of-the-century prose, but there’s a punk-rock provocation at its core. My editor said: “Do you realise there are no physical descriptions in the first part?” And I was like, yes, it’s very intentional: nobody has a body, nobody has a face, and in the first 160 pages there’s only one line of dialogue – one word, one letter, “I”. It was a formal dare, almost like an Oulipian constraint. As the book moves forward, we end up inside a body and a mind, and I thought that journey would be more powerful after a highly abstracted opening. The novel is about who has a voice: who, throughout history, has been given a megaphone. Who has been gagged? Rather than thematise that in an expository way, I thought it would be more vivid – and fun – for readers to be presented with this polyphonic arrangement of four voices in succession and gently ask them to question why we trust one over the other.

That word “trust” resonates throughout the novel, not least in defining the relationship between you and the reader as you jump from one version of the story to the next. When did you know it should be the title?
It came to me on an elliptical trainer at the gym! I was two-thirds into the writing and I was desperate because I didn’t yet have a title, but I knew I wanted it to be as layered as the book. It was like an epiphany; I typed it into my phone, very excited.

Are you deliberately moving forward through US history one novel at a time?
No, the connection with In the Distance dawned later. I didn’t think, oh, I’ll do the territorial and institutional consolidation of the United States in the 1850s and then I’ll do its financial consolidation and imperial expansion. But I suppose I am drawn to how the US is obsessed with presenting itself as a fiction. The genre of the western exoticises America for Americans themselves, and I see that too in depictions of the Roaring 20s and the ensuing Great Depression.

Drilling into the ideological strata of these fossilised tropes is what fascinates me. I have no interest in sharing my own lived experience and I’m not into the testimonial turn literature has taken; I find the premise of immediacy suspicious. Literature is mediated – by language – and I’m more interested in doubling down on that mediation. I find the impossibility of us truly touching one another through language not only heart-rending but aesthetically more interesting than the [notion of] immediate connection. If ever I find myself on the page, I view it as an immense failure. For me, writing and erasing myself are one and the same; a sentence succeeds because it conjures up something other than me.

How involved are you with HBO’s forthcoming adaptation of Trust?
Kate Winslet is producing it; we’re closely in touch and she has all these amazing ideas. At first I was excited to write it, but I realised I’d be better off as an executive producer after a couple of really big sleepless nights deciding what to do. It seemed creatively more honest to write a new book rather than stay a year or two more with Trust. So I’m fully engaged and have a say, but I’m not writing it.

Tell us what you’ve enjoyed reading lately.
Caoilinn Hughes’s The Alternatives [out next year] is a big philosophical novel that’s super fun and unexpected at a sentence-by-sentence level. It’s about four orphaned sisters in Ireland who are now adults, and one of them is having a sort of meltdown, but it’s all around climate change – it’s very engaging and non-didactically done.

Which writer first inspired you?
I started out by writing bad imitations of Jorge Luis Borges. Now I can only take him in small doses because every time I go back to him I find he colonises my mind. Reading his story The Library of Babel in my early teens was the gateway, for sure. In every living room of certain middle-class households in a certain period in Argentina you’d see the thick green tome [of his collected stories]. I was pretending to read it, then one day I actually did. The ground opened up under my feet and I was staring into an immensity I didn’t know was there.

• Trust by Hernan Diaz is published by Picador (£9.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply