Build vs buy

The decision turns on one question: is trading technology genuinely your differentiator? For most desks the platform is table stakes and the edge is in strategy and execution, not in re-implementing trade capture, valuation, risk, scheduling, and settlement. Build what is uniquely yours; buy what is table stakes.

Buy the platform when you need the full lifecycle working reliably, quickly, and at low risk. Building capture, valuation, risk, scheduling, and settlement from scratch is a multi-year undertaking with a large and unglamorous surface area, and it rarely pays back because none of it differentiates you. The lifecycle is a solved problem; buying it lets your scarce engineering effort go where it actually creates an edge.

Build the pieces that are genuinely unique to your edge, a proprietary forecasting model, a bespoke analytic, a novel strategy, and build them on top of a platform’s API rather than reinventing the lifecycle underneath them. The test is simple: if a capability is a source of competitive advantage, build it; if it is undifferentiated plumbing, buy it.

An API-first platform lets you buy the lifecycle and build only what differentiates you, composing the two cleanly through supported interfaces. This is usually the lowest-risk path to a real edge: the platform carries the undifferentiated weight, and your engineers build the thin, high-value layer on top.

python# Build only your edge; call the platform API for the undifferentiated lifecycle.
from gravitas import Client

client = Client(api_key=KEY)

def my_proprietary_signal(market):
    ...                                   # THIS is your edge: build it
    return signal

def act_on_signal(signal):
    positions = client.positions.live()   # bought lifecycle: don't rebuild
    hedge = size_hedge(signal, positions) # your logic
    client.trades.book(hedge)             # bought lifecycle: capture, value, risk

Teams that choose to build often underestimate the ongoing cost, not of the first version, but of keeping it correct as markets, instruments, and regulations change for years. A bought platform amortises that maintenance across every customer; a built one carries it alone. Include that lifetime maintenance in the comparison, not just the cost of the initial build.