Transport giant ComfortDelGro Corp posted a 19.6 per cent drop in first-quarter earnings to $66.3 million on the back of plunging investment income.

The drop in investment income was because of a non-recurrence of $10 million in special dividends from fully owned Cabcharge Australia last year.

ComfortDelGro, a Singapore-based listed group with a global presence, said revenue for the first three months grew 1 per cent to $878.8 million, aided by positive foreign exchange translation.

Besides the drop in investment income, operating expenses inched upwards by 1.8 per cent to $783.1 million. As a result, earnings per share fell by 20.1 per cent to 3.06 cents. Net asset value per share rose by 2.2 per cent to 123.63 cents.

Its operating margin, as defined by earnings before interest, tax and depreciation, shrank to 22 per cent, down from 23.4 per cent at the same time last year.

The group said revenue from its public transport business - largely subsidiary SBS Transit's bus and rail operations here - had improved, but this was offset by weaker showings in almost every other division.

SBS Transit posted a 63.7 per cent gain in net profit to $16.8 million for the first quarter.

ComfortDelGro's Singapore taxi business continued to be battered by the disruptive private-hire players, although there are signs of a turnaround in the second quarter of this year.

Directors expect revenue from the taxi business to stabilise with "the rationalisation of the competition landscape in Singapore".

The group had cash and equivalent of $635.3 million, largely unchanged from $639.2 million. Total equity increased by $69.4 million to $3,107.2 million.

Chief executive Yang Ban Seng said: "The first quarter of 2018 has been very eventful for us. We have inked several acquisitions as we step up our pace of mergers and acquisitions. A total of $123 million has been spent on M&As in 2018 so far - as compared with $166 million in the preceding five years."

He said the group will continue to seek acquisition opportunities.

Mr Yang noted that the decline in ComfortDelGro's taxi business had been "slower" in the first quarter.

"With the reduced subsidy and incentives for drivers and riders by ride-hailing app operators, and the (Land Transport) Authority's review of regulations for private-hire vehicles, we believe that the competition will be on a more level playing field going forward. This is a positive development."