This is probably not surprising since the two commodities they are involved with are also enjoying extremely high world prices.
Nevertheless, the performance of these two stocks is a sign of the greatly increased foreign investor confidence in PNG at a time when national elections are being held for the eighth parliament, traditionally a time of significant conflict.
Traditionally in past years, PNG stocks have generally suffered a discount because of perceptions of political and country risk.
But this does not appear to be the case at present, with many junior explorers reporting they have had no difficulty raising funds, particularly in the UK and Canadian markets for activities in PNG.
In recent weeks, major American fund managers have become significant stakeholders in both Oil Search and Lihir, signalling their confidence that these companies will continue to be good corporate performers.
Underlying this is also their confidence that the next government that will be formed in July is not likely to adversely affect the investment climate.
The fiscal situation in PNG has been extremely good over the last four years and the country has enjoyed its longest period of sustained growth.
Foreign debt is now at much more manageable levels and foreign exchange reserves are at an all-time high, providing confidence that the kina will remain stable.
Highlands Pacific and Emperor Mines are facing problems of their own making but this has not affected investor sentiment generally.
Among exploration stocks, two that are doing very well at present are Allied Gold, which will commence gold production later this year, and Marengo Mining, where a resource upgrade and a preliminary pre-feasibility study has created some excitement in the market.
In recent weeks, the market capitalisation for Lihir Gold has surpassed $A5 billion, a first for any listed company with mainly PNG operations.
The market capitalisation for Oil Search is also standing at a near record $4 billion.
Clearly both companies still have a way to go in terms of market valuation since Lihir expects to be producing a million ounces of gold from its PNG operations in about three years time, with the stock likely to get an additional tick next year if its Ballarat mine in Victoria also commences gold production.
Oil Search, for its part, is providing the cornerstone for two separate large liquefied natural gas projects that are under study by ExxonMobil and British Gas, respectively. A third proposal involving a mid-size plant of around a million tonnes a year could also involve Oil Search.
In the last few years, Oil Search has also become active in the Middle East and North Africa. In Yemen, it make an oil discovery with its first well and operations became cashflow positive in the first year.
It now looks like repeating this success in Egypt, where initial exploration has led to expectations of oil production in the third quarter of this year.