For the benefit of anybody who's reading these threads for their educational value, and who may not understand this participant's comment:
I believe he's referring to the "down-gap" between the intraday low of $7.02 on 5-31-13, Friday, and the opening at $6.28 on the next trading day, which was the following Monday, 6-3-13.
It's a principle of technical analysis that price "gaps" are often "filled" by "retracements" of the price movements which created the gaps. When prices "gap" up or down, in the sense that one day's opening is either higher than the intraday high of the prior trading day (an up-gap) or lower than the intraday low of the prior trading day (a down-gap) it's observed that prices often are unable to proceed further up or down for long until they've "retraced" the gaps, by returning to the levels at which the gaps began. In the case of an up-gap, this may mean that, although the price will continue to rise for a while after it gaps up, it may lose momentum and then decline until it falls back to the level from which it first gapped up. In the case of a down-gap, the price may continue to fall after it gaps down, but it may stabilize, then rise, until it returns to the level from which it gapped down.
Both in the cases of up-gaps and of down-gaps "filling" a gap by returning to the level at which the gap began doesn't mean the price will continue to rise or fall past the level at which the gap began. Once a gap's been filled prices often reverse, and then continue to trend up or down as they'd been doing when the gaps occurred. In this case, the price of NBG might reverse downward and continue to fall once it "fills" its $7.02 to $6.28 down-gap of 5-31-13, Friday to 6-3-13, Monday by rising to $7.02 from below.