Coin stacks and chart graphs on a chessboard background. Horizontal composition with selective focus and copy space.

While many retailers have been sobbing in recent years, investors in Boohoo Group PLC (LON:BOO) were crying tears of joy this week as the online fashion chain’s shares hit a new all-time high.

The stock has risen 17% since Monday’s open to 283p thanks to a bullish trading update where the Nasty Gal and PrettyLittleThing owner said full-year results were now expected to be “ahead of previous guidance” after strong growth in its first half.

Boohoo’s ascent also meant it was now AIM’s largest company with a market cap of almost £3.3 billion, well ahead of its peer and former king of AIM, ASOS PLC (LON:ASC), on £2.1 billion.

The last six months have seen an almost inverse performance in the shares of the two retailers, with ASOS tumbling 23% compared to Boohoo’s 58% upsurge.

Elsewhere on AIM this week, the company that was recently the junior market’s top dog, Burford Capital Limited (LON:BUR), was back in the news as it came out swinging against snipes from hedge fund Muddy Waters.

The San Francisco-based short seller accused Burford of overstating the performance of its $7.4 million investment in Napo Pharmaceuticals, which has recently attracted media scrutiny due to the involvement of fund giant Invesco as an investor in the US biotech and in Burford.

Burford fired off a rebuttal on Monday, including stressing that Napo was “not referred to Burford by Invesco” and that the investments in Napo and Burford were overseen by different Invesco fund managers.

Investors seemed relatively unmoved by the back and forth, with the shares dipping 1.6% to 688p over the week, bringing little cheer for Burford as its shares continue to wallow 50% below their level before the first Muddy Waters attack in early August.

Overall, the AIM All-Share index was up 1% at 880.7 over the week, compared to a 0.8% increase for the FTSE 100 to 7,267.3.

Another small cap firm on the up this week was Range Resources Limited (LON:RRL), which, having sunk to an all-time low last month, rocketed back 156% to the giddy heights of 0.05p after the oil and gas outfit agreed to sell its assets in Trinidad in exchange to a lender in exchange for all its outstanding debt and a $2.5 million cash payment.

Spirits maker Distil PLC (LON:DIS) cheered a 3% rise in its shares to 0.85p after announcing that it soon launch a pre-mixed rum and coke drink in collaboration with Franklin and Sons.

Filtration firm Amiad Water Systems Ltd (LON:AFS) also gushed 23% higher to 270p as it confirmed reports it was in discussions with major shareholder FIMI Opportunity Funds about a potential investment.

Hydrogen Group PLC (LON:HYDG) saw its shares float 17% higher to 55p as the recruitment firm reported a 51% rise in underlying pre-tax profits for its first half, as well as a 20% hike in its interim dividend to 0.6p.

Meanwhile, plastic components maker Synnovia PLC (LON:SYN) soared 41% to 123p on news that it was to go private in a deal valuing the firm at £48.8mln.

A fund advised by California-based Camelot Capital is offering 125p a share, a 43% premium to Synnovia’s closing price last Friday.

Among the fallers, shares in software group Altitude Group PLC (LON:ALT) performed a rapid descent, tumbling 43% to 56p after the firm said revenue in the first half has not “accelerated as quickly as envisaged” despite growing at what it said was a “historically record pace”.

Clothing retailer Quiz PLC (LON:QUIZ) also slumped 15% to 16p as it reported challenging trading conditions had continued to hit sales over the summer months.

Finally, app and mobile game firm Mobile Streams PLC (LON:MOS) announced its intention to delist from AIM and re-register as a private company, sending the shares plunging 65% to 0.07p.