Here are well-known / market-leading stockbroking firms based in Colombo (widely used by retail, high‑net‑worth and institutional investors). I’ve included a short note and a source for each firm so you can check services, branch coverage and contact details.

• First Capital Equities (First Capital Holdings) — full‑service broker with in‑house research and wide product coverage. (firstcapital.lk)
• NDB Securities (NDBS) — one of the long‑standing brokers in Sri Lanka with recognised research and institutional capabilities. (lk.linkedin.com)
• Capital TRUST Securities — large retail client base, multi‑branch network and high turnover on the CSE. (capitaltrust.lk)
• Lanka Securities — established member‑firm of the Colombo Stock Exchange, offers research and retail/institutional broking. (lankasecurities.com)
• Asia Securities / Asia Capital (Asia Securities (Pvt) Ltd) — active CSE member firm and widely used broker. (csclk.blogspot.com)
• Bartleet Religare Securities — long‑standing CSE member firm and broker. (startcse.blogspot.com)
• John Keells Stockbrokers / brokers within large groups (e.g., John Keells Group related brokerage services) — part of major conglomerates offering broking & wealth services. (startcse.blogspot.com)
• Capital Alliance Securities / Capital Alliance group — investment bank / broker with primary dealer and securities services. (en.wikipedia.org)
• CT Smith, Acuity, SMB and other established CSE member brokers — notable regional/retail brokers used by many investors. (startcse.blogspot.com)

Notes and next steps

• The Colombo Stock Exchange (CSE) maintains member and trading‑member lists and the Securities and Exchange Commission (SEC) of Sri Lanka lists licensed market intermediaries — check those for the official, up‑to‑date roster and any regulatory history. (investsrilanka.biz)
• “Top” can mean different things (highest turnover, biggest client base, best research, lowest fees, best online platform). If you tell me which criteria matter most (fees, research, online trading, branches, institutional services), I can compare 3–5 brokers and pull their fee schedules, platform links and contact details.