Nakumatt has grown from a single dusty megastore in Industrial Area [opposite Nyayo Stadium] into EAC's largest retailer. It dominates Kenya but has opened stores in Uganda [outshining the older Uchumi], Rwanda & will soon open 3 stores in Tanzania. I am sure Burundi & South Sudan are not far off.
Even Uchumi [which expanded into Kampala many years ago] plans to open new locations in Uganda to mirror Nakumatt's expansion. There are runors about expanding to Tanzania as well.
KenolKobil has pursued an expansion strategy for years & the regional footprint has become more important to KK over the years. It just announced a significant new acquisition in Tanzania. By 2015, KK's regional operations > Kenya operations. KK has established a subsidiary as far south as Mozambique. It trades as Kobil [no more "Kenya Oil" aka Kenol] in the region.
Kenya Commercial Banl (styled as 'KCB') was the first Kenyan bank to venture into EAC with an operation in Tanzania. KCB does not use "Kenya" for easier acceptance to other markets including Rwanda, Uganda & South Sudan.
A close [& more successful] competitor is Diamond Trust Bank [styled as DTB]. Unlike KCB, DTB acquired majority stakes in its sister firms [under the aegis of AKFED] over time & is not a unified brand in all EAC countries except Rwanda.
Equity Bank purchased Uganda Microfinance Ltd & is now among the fastest growing banks in Uganda. Greenfield operations are quite successful in South Sudan. This remains a bank to watch.
Mid-tier banks like NIC Bank [no more the verbose National Industrial Credit Bank] and I&M Bank [no more the verbose Investments & Mortgages Bank] have expanded into Tanzania. Seems Ugandan banks are over-priced for them or the smart money says the potential in socialist leaning Tanzania is greater.
***I&M Bank took an interesting route by acquiring 50% of First City Bank with a Mauritian conglomerate (CIEL) which has extensive operations in the Tanzania & Zambia. My gut tells me that they will acquire a Zambian operation since Tanzania & Zambia share an extensive border & trade relations. The Tanzanian acquisition ['C&F Bank' now renamed 'I&M Tanzania'] is a joint venture between I&M and CIEL.
AKFED has used the Kenyan operations to support & eventually acquire other EAC businesses.
Jubilee Insurance Company had a path similar to DTB. The Tanzania & Uganda operations are now subsidiaries of Jubilee Kenya but I expect the Kenya operation to become Jubilee Africa but HQ's in Nairobi.
Tourism Promotion Services (TPS aka Serena) is a Kenya based firm but grew 'East African' by acquiring TPS properties in Tanzania & is now TPSEA. The brand name "Serena" is owned by AKFED. There are Serena properties [not part of TPSEA] in Uganda, Rwanda & Mozambique.
[BTW, the Kampala Serena puts the Nairobi Serena to shame!]
Like the path followed by other AKFED firms, I expect TPS(U) & TPS(Rw) will merge into TPS(EA) within a few years. Maybe even the Polana Serena in Mozambique. Of course, add a name change to TPS Africa soon thereafter.
The brand name "Serena" is owned by AKFED & there are Serena properties in Afghanistan, Pakistan & Tajikistan but these have little connection to the original TPS.
Another AKFED baby is Nation Media Group which has extensive operations in Uganda & Tanzania. Unlike DTB or TPSEA, these were greenfield operations but seem to be doing well. I am sure there are plans to head further west. Museveni was not happy with NMG but since AKFED is a major investor in Uganda [Air Uganda, Bujagali, TPS/Serena, DTB, Jubilee, etc] he has eased off.
Sameer Group [naushad merali's group] has interests in various countries. Except for the perennial under-performers in Kenya, I know little of them but Sameer recently bought a £15,000,000 call-center in the UK.
TransCentury has made a splash & excepts to list in a few years. They are in Tanzania [through a NSE-listed EA Cables subsidiary as well as direct ownership of Chai Bora], Uganda [RVR = Rift Valley Railways] & South Africa [Kewberg Cables]. I believe they are poised to expand even further & faster over the next few years especially through the revamp of RVR.
Cooper Motors Corporation (nowadays CMC Group) has operations in Uganda & Tanzania.
Kenya's largest firm East African Breweries [which changed from 'Kenya' Breweries to 'East African' Breweries after making forays into Uganda & Tanzania] looked into expansion into Ethiopia as well. EABL broke up with SABMiller controlled Tanzania Breweries by buying a majority stake in Serengeti Breweries.
*** KBL became EABL which became KBL (again) in the 1970s after the nationalization of Uganda Breweries during the days of the murderous buffoon idi amin as well as nationalization by the socialist fools who ran Tanzania. With the loss of its Tanzanian & Ugandan operations [leaving only Kenya] EABL changed its name to KBL. And now back to EABL.
Kenya Airways (KQ) has the largest pan-African footprint & in some countries it is the de facto international airline! KQ in West Africa provides a 'matatu' service by hopping in & out of multiple cities boarding & disembarking passengers before reaching its final destination!
Even the small firms are in the act like NSE-listed firm Car & General (C&G) has operations not only in Tanzania & Uganda but in India as well!
There are numerous smaller, private or family firms with interests in EAC. These may fly under the radar since they might not share a common name or want to (legitimately) remain out of the spotlight.