UPDATE 3-Carrefour Brasil IPO prices at bottom of range -sources

(Updates with pricing)

BOGOTA/SAO PAULO, July 18 (Reuters) - Grupo Carrefour Brasil SA on Tuesday priced Brazil's largest initial public offering this year at 15 reais per share, the bottom of a suggested price range, two people familiar with the matter said, due to concern over a stretched valuation.

One of the people, who asked for anonymity, said price was enough to "comfortably" cover the minimum amount of shares put on offer.

Carrefour Brasil, a unit of France's Carrefour SA and Brazil's largest supermarket chain, and shareholders would secure around 4.5 billion reais ($1.4 billion) with the transaction. That could increase to 6 billion reais if they sell supplementary and additional allotments in full.

Media representatives for Carrefour Brasil declined to comment.

At 15 reais per shares, Carrefour Brasil would trade at a discount against rival GPA SA in terms of enterprise value over earnings before interest, tax, depreciation and amortization, a metric known as EV/EBITDA. Other multiples, such as sales over EBITDA, yield a premium for Carrefour Brazil.

Investors were reluctant to bid at the top half of the 15-19 reais suggested range for a company that lacks a substantial competitive advantage, fund managers said.

Still, the IPO should help Carrefour Brasil add muscle to take on GPA, whose food division has recovered amid slowing appliance sales. Carrefour recently surpassed GPA as Brazil's No. 1 diversified retailer in sales.

The transaction seals the first phase of an alliance between Carrefour and Brazilian retail tycoon Abilio Diniz, which started in 2014. Diniz, whose family founded GPA, is Carrefour's third-largest shareholder and has a seat on its board.

Carrefour Brasil's IPO is the first of two such offerings this week, making it the busiest for share offerings since mid-February.

The separate offering of Brazilian depositary receipts (BDRs) in Colombia-based pharmaceutical firm Grupo Biotoscana SA has investors willing to place three times the amount of shares on offer at the mid-point of a 24.50-28.50 reais price range, two people with knowledge of the deal said.

Pricing of the offering, originally scheduled for Tuesday, was delayed to Friday after Biotoscana revised its financial statements in response to a regulatory inquiry over the accounting of its 2015 purchase of Laboratorio LKM.

Investors are wary of Brazilian IPOs after new issues failed to deliver promised returns over the past decade.

Less than one-third of the 115 IPOs priced since the start of 2007 yielded returns above Brazil's interbank lending rate, Thomson Reuters data shows.

($1 = 3.1580 reais) (Reporting by Guillermo Parra-Bernal and Bruno Federowski; Additional reporting by Dominique Vidalon in Paris and Tatiana Bautzer in São Paulo; Writing by Guillermo Parra-Bernal and Bruno Federowski; Editing by Tom Brown and Sandra Maler)