The Australian share market has given back its early gains, thanks to Telstra's share price plunging to a five-year low.

The benchmark ASX 200 index jumped 18 points in the first hour of trade.

But then it also fell by as much as 13 points in the early-afternoon (around 2:00pm AEST).

The ASX 200 was tracking 0.2 per cent higher at 5,678 by 3:00pm (AEST), while the broader All Ordinaries index was up 0.1 per cent at 5,741.

Contributing to today's weak performance were the big four banks being sold off — CBA (-0.4 per cent), Westpac (flat), NAB (-0.1 per cent) and ANZ (-0.3 per cent).

In addition, Australia's large mining companies were trading mixed.

BHP was up 0.2 per cent, Rio Tinto had gained 0.1 per cent, while Fortescue Metals had fallen 0.1 per cent.

The Australian dollar had risen 0.45 per cent to 79.83 US cents. It received a boost from better-than-expected housing and construction data.

Telstra to blame for ASX weakness

The telco giant's shares had fallen 6.1 per cent to $3.60.

Telstra has been today's second-worst performing major stock, and its share price has not been this low since June 2012.

The first reason for the low share price is that Telstra is trading ex-dividend today, which means new buyers of its shares will not receive the latest dividend.

Secondly, Telstra announced that NBN Co has shot down its plans to monetise up to $5.5 billion worth of future income from national broadband network (NBN) compensation and access payments.

The telco said the proposal had been "well progressed and supported by equity and debt investors".

However, the roadblock is that "technical consents from NBN Co will not be forthcoming".

Citi analyst David Kaynes said that means shareholders are likely to get even less cash back from the telco, which already announced a near-30 per cent cut to future dividends at its most recent results.

"At its results announcement, Telstra articulated plans to monetise 40 per cent of its long term NBN receipts, with the transaction expected to generate $5-5.5 billion," he wrote in a client note.

"Telstra had hoped to use the funds to repay $1 billion of debt and use the remainder for capital management.

"In our view, this means that the proposed share buybacks that Telstra had intended to fund with this transaction are unlikely to proceed."

Ramsay and Boral also disappoint the market

Ramsay Health Care and Boral reported their financial results, and they were not well-received by the market.

In fact, both companies' shares are among the top ten worst performers today.

Ramsay's share price fell 4.9 per cent to $68.34, after reporting its full-year core net profit lifted 12.7 per cent to $542.7 million.

The profit uplift was driven by an increase in hospital admissions, and earnings from its Australian operations — with revenue up 7 per cent to $4.7 billion.

The private hospital operator group declared a fully-franked final dividend of 81.5 cents.

As for Boral, it reported a full-year net profit of $297 million, up 16 per cent over the previous year.

However, Boral's share price fell 3.7 per cent to $6.58.

The building materials company's largest division, Boral Australia, saw an 11 per cent lift in EBIT to $349 million.

"The Australian business delivered volume and margin improvements, benefiting from strong east coast residential activity," said the company's CEO and managing director Mike Kane.

Boral declared a final dividend of 12 cents per share (50 per cent franked) — which was 0.5 cents higher than last year.