BOGOTA, Jan 12 (Reuters) - Colombia's Grupo Gilinski is on the verge of becoming the second-largest shareholder in Grupo SURA after securing 25.42% of the investment company's shares in a public acquisition offer, the Colombian Stock Exchange said on Wednesday.

Grupo Gilinski, via JGDB Holding SAS and with the financial backing of First Bank of Abu Dhabi, initially sought to buy between 25.344% and 31.68% of Grupo SURA's shares.

Grupo Gilinski, which offered $8.01 per Grupo SURA share, snatched up 118.9 million shares out of a total 467.9 million available shares in the acquisition, which closed on Tuesday, in a transaction that could exceed $952.5 million.

Acceptances are subject to the validation and approval of the Colombian Stock Exchange.

If the transaction is approved Grupo Gilinski will become Grupo SURA's second-largest shareholder after Grupo Argos , which controls 27.6% of the company.

Banker Jaime Gilinski, along with support of Abu Dhabi's Royal Group, also launched a public acquisition offer to buy up to 62.625% of shares in Nutresa, the largest processed food producer in Colombia, in a deal that could be worth some $2.22 billion.

Grupo Gilinski offered $7.71 per Nutresa share.

Both Sura and Nutresa fall under the umbrella of Colombia's largest conglomerate, Grupo Empresarial Antioqueno (GEA), which also controls more than 100 companies including industrial conglomerate Grupo Argos, energy generator Celsia and bank Bancolombia.

The offer for Nutresa will close on Wednesday. By Tuesday Grupo Gilinski had secured 16.47% of Nutresa's 458 million shares.

Neither Grupo Gilinski, Grupo SURA, nor Nutresa were immediately available to comment.

(Reporting by Luis Jaime Acosta in Bogota Writing by Oliver Griffin Editing by Matthew Lewis)