Updated from 1:34 p.m. EDT

Two weeks after swearing off interest in the London Stock Exchange, the

Nasdaq

I:IXIC

said Tuesday that it is in possession of almost 15% of the U.K. company's outstanding shares.

The Nasdaq said it owns 38.1 million LSE shares, having bought the vast majority from the exchange's biggest institutional shareholder,

Ameriprise

(AMP) - Get Report

unit Threadneedle Asset Management.

The Nasdaq said it acquired 35.4 million shares from Threadneedle and another 2.7 million in a separate purchase. The total price for the stake was $782 million.

On March 31, the Nasdaq withdrew a $4.2 billion offer for the whole LSE in a move that many believed ended the international takeover drama for the exchange. In a brief statement released at the time, the Nasdaq said that it "no longer intends to make an offer for the LSE." It didn't give a reason.

However, the New York-based company said it "reserved the right" to renew the offer under certain circumstances over the next six months.

The LSE interest announced Tuesday actually equals 14.99% of the LSE's outstanding stock. According to U.K. rules governed by the London Takeover Panel, that's the maximum stake a company can acquire on the open market within one week's time. Representatives of the Nasdaq would not comment on when the stake was bought.

The same rules say a company can raise its stake to just below 30% of the target before it needs to launch a formal offer to all shareholders

One way or the other, the Nasdaq has positioned itself for a potentially lucrative stake in the company. At the very least, the 1,175 pence per share it paid for the 14.99% stake sets a new floor for a bid for the company if other exchanges decide to explore an acquisition.

The Nasdaq publicly disclosed its now-withdrawn unsolicited offer for the LSE on March 10. The bid, which comprised cash and looked to be contingent on a large slug of bank financing, was 60% higher than a previous offer for the London exchange made by Australia's Macquarie Bank. It was 72% above the LSE's closing price before the Macquarie bid surfaced.

The LSE recommended shareholders reject both the Nasdaq and Macquarie offers.